Disable fail-fast on pushing images to docker cache (#24005)

There is an issue with pushing cache to docker registry that
is connected to containerd bug but started to appear more
frequently recently (as evidenced for example by
https://github.community/t/buildx-failed-with-error-cannot-reuse-body-request-must-be-retried/253178
). The issue is still open in containerd:
containerd/containerd#5978.

Until it if fixed, we disable fail-fast on pushing cache
so that even if it happens, we just have to re-run that single
python version that actually failed. Currently there is a much
lower chance of success because all 4 build have to succeed.

.github/workflows/ci.yml

@@ -1661,6 +1661,7 @@ ${{ hashFiles('.pre-commit-config.yaml') }}"
       - docs
     if: needs.build-info.outputs.mergeRun == 'true'
     strategy:
+      fail-fast: false
       matrix:
         python-version: ${{ fromJson(needs.build-info.outputs.pythonVersions) }}
     env: