Update and consistently pin all github actions

[fwilhe]

Follow up for gardenlinux/gardenlinux#4015

Needed to avoid this error

Error: The actions actions/setup-python@v5 and snok/install-poetry@v1 are not allowed in gardenlinux/gardenlinux because all actions must be from a repository owned by your enterprise, created by GitHub, verified in the GitHub Marketplace, or match one of the patterns: aws-actions/configure-aws-credentials@*, azure/k8s-set-context@v*, azure/login@*, codecov/codecov-action@*, docker/setup-qemu-action@*, gardenlinux/*, gardenlinux/workflow-telemetry-action@*, golangci/golangci-lint-action@*, google-github-actions/auth@*, jdx/mise-action@*, opentofu/setup-opentofu@*, oras-project/setup-oras@*, peaceiris/actions-gh-pages@*, peaceiris/actions-gh-pages@v3, pmeier/pytest-results-action@*, psf/black@stable, redhat-plumbers-in-action/differential-shellcheck@*, snok/install-poetry@*, softprops/action-gh-release@v2, toanju/package-build/*. All actions must also be pinned to a full-length commit SHA.