On the python side (aka backend) you'll need to update your venv.
The following will pip install the versions specified in the constraints file and attempt to uninstall the "wrong" versions.
CONSTRAINTS_FILE=https://dist.plone.org/release/6.0.6/constraints.txt
pip install -U pip wheel setuptools -c ${CONSTRAINTS_FILE}
pip install Plone -c ${CONSTRAINTS_FILE}
# and your extra packages
pip install <extra_package> -c ${CONSTRAINTS_FILE}
See below a diff of the constraints in versions 6.0.5 and 6.0.6. Please note that Plone 6.0.6 uses Zope 5.8.3. If you need Zope 5.8.4 you will need to run pip install Zope==5.8.4 without constraints. But this might mess your versions if there are other dependencies (which AFAICS is not currently the case with Zope==5.8.4)
$ diff -y --suppress-common-lines |
<(curl -s https://dist.plone.org/release/6.0.5/constraints.txt) |
<(curl -s https://dist.plone.org/release/6.0.6/constraints.txt)
Acquisition==4.13 | Acquisition==5.0
CacheControl==0.12.11 <
Deprecated==1.2.13 | Deprecated==1.2.14
Paste==3.5.2 | Paste==3.5.3
Persistence==3.6 | Persistence==4.0.post1
Plone==6.0.5 | Plone==6.0.6
Products.BTreeFolder2==5.0 | Products.BTreeFolder2==5.1
Products.CMFPlone==6.0.5 | Products.CMFPlone==6.0.6
PyGithub==1.58.1 | PyGithub==1.58.2
PyJWT==2.6.0 | PyJWT==2.7.0
Pygments==2.14.0 | Pygments==2.15.1
Record==3.6 | Record==4.0
Sphinx==6.1.3 | Sphinx==6.2.1
ZConfig==3.6.1 | ZConfig==4.0
Zope==5.8.2 | Zope==5.8.3
beautifulsoup4==4.11.2 | beautifulsoup4==4.12.2
> cachecontrol==0.13.1
certifi==2022.12.7 | certifi==2023.5.7
cryptography==40.0.2 | cryptography==41.0.1
filelock==3.12.0 | filelock==3.12.1
icalendar==5.0.5 | icalendar==5.0.7
launchpadlib==1.11.0 <
lazr.restfulclient==0.14.5 <
lazr.uri==1.0.6 <
packaging==23.0 | packaging==23.1
pip==23.0.1 | pip==23.1.2
plone.app.caching==3.1.1 | plone.app.caching==3.1.2
plone.app.content==4.0.1 | plone.app.content==4.0.2
plone.app.layout==4.0.5 | plone.app.layout==4.0.6
plone.app.locales==6.0.14 | plone.app.locales==6.0.15
plone.app.mosaic==3.0.3 | plone.app.mosaic==3.1.3
plone.app.portlets==5.0.5 | plone.app.portlets==5.0.6
plone.app.querystring==2.0.4 | plone.app.querystring==2.0.5
plone.app.relationfield==3.0.2 | plone.app.relationfield==3.0.3
plone.app.standardtiles==3.1.1 | plone.app.standardtiles==3.1.2
plone.app.theming==5.0.3 | plone.app.theming==5.0.4
plone.app.upgrade==3.0.5 | plone.app.upgrade==3.0.6
plone.app.users==3.0.2 | plone.app.users==3.0.3
plone.app.z3cform==4.2.0 | plone.app.z3cform==4.2.1
plone.batching==2.0.5 | plone.batching==2.0.6
plone.memoize==3.0.1 | plone.memoize==3.0.2
plone.namedfile==6.1.0 | plone.namedfile==6.1.1
plone.outputfilters==5.0.2 | plone.outputfilters==5.0.3
plone.portlet.collection==4.0.2 | plone.portlet.collection==4.0.3
plone.releaser==2.0.0 | plone.releaser==2.0.1
plone.restapi==8.39.1 | plone.restapi==8.40.0
plone.staticresources==2.0.11 | plone.staticresources==2.1.3
plone.subrequest==2.0.3 | plone.subrequest==2.0.4
plone.volto==4.0.8 | plone.volto==4.0.9
plonetheme.barceloneta==3.0.2 | plonetheme.barceloneta==3.1.3
pyOpenSSL==23.1.1 | pyOpenSSL==23.2.0
python-dotenv==1.00 | python-dotenv==1.0.0
python-gettext==4.1 | python-gettext==5.0
pytz==2022.7.1 | pytz==2023.3
requests==2.28.2 | requests==2.30.0
requests-toolbelt==0.10.1 | requests-toolbelt==1.0.0
rich==13.3.4 | rich==13.4.1
robotframework==6.0.2 | robotframework==6.1
robotframework-seleniumlibrary==6.0.0 | robotframework-seleniumlibrary==6.1.0
selenium==4.9.0 | selenium==4.9.1
setuptools==67.6.1 | setuptools==67.8.0
soupsieve==2.4 | soupsieve==2.4.1
tempstorage==5.2 | tempstorage==6.0
towncrier==22.12.0 | towncrier==23.6.0
trio-websocket==0.10.2 | trio-websocket==0.10.3
trove-classifiers==2023.4.25 | trove-classifiers==2023.5.24
types-PyYAML==6.0.12.8 | types-PyYAML==6.0.12.10
urllib3==1.26.15 | urllib3==2.0.2
z3c.pt==3.3.1 | z3c.pt==4.0
zdaemon==4.4 | zdaemon==5.0
zodbpickle==2.6 | zodbpickle==3.0.1
zope.annotation==4.8 | zope.annotation==5.0
zope.browser==2.4 | zope.browser==3.0
zope.cachedescriptors==4.4 | zope.cachedescriptors==5.0
zope.component==5.1.0 | zope.component==6.0
zope.configuration==4.4.1 | zope.configuration==5.0
zope.container==5.0 | zope.container==5.1
zope.contentprovider==4.2.1 | zope.contentprovider==5.0
zope.contenttype==4.6 | zope.contenttype==5.0
zope.datetime==4.3.0 | zope.datetime==5.0.0
zope.deprecation==4.4.0 | zope.deprecation==5.0
zope.dottedname==5.0 | zope.dottedname==6.0
zope.globalrequest==1.6 | zope.globalrequest==2.0
zope.i18n==4.9.0 | zope.i18n==5.0
zope.i18nmessageid==5.1.1 | zope.i18nmessageid==6.0.1
zope.processlifetime==2.4 | zope.processlifetime==3.0
zope.ptresource==4.3.0 | zope.ptresource==5.0
zope.structuredtext==4.4 | zope.structuredtext==5.0
zope.testbrowser==5.6.1 | zope.testbrowser==6.0
zope.testrunner==5.6 | zope.testrunner==6.0
zope.traversing==4.4.1 | zope.traversing==5.0
zope.viewlet==4.3 | zope.viewlet==5.0