Add release automation to update getting started guide

[austinvazquez]

Issue #, if available:
Updating the version in the getting started guide is currently a manual step for every release. It would be nice to have automation to generate the PR so maintainers only have to approve and merge the pull request.

Description of changes:
This change adds a workflow to open a pull request to update the version in the getting started guide when a release is made.

Testing performed:
Pushed workflow to fork and created a release tag to show workflow opened a PR to update the getting started version.

Automated version PR - austinvazquez#29
Release used to trigger automation - https://github.com/austinvazquez/soci-snapshotter/releases/tag/v0.6.1-alpha.0
GitHub Action workflow run - https://github.com/austinvazquez/soci-snapshotter/actions/runs/9208357812

Mock workflow runs in pull request on changes to GitHub Actions workflow file and asserts the changes are made to update the version.

Alternatives considered:

1. An approach which creates the PR once the release tag is pushed. i.e. the existing release workflow
   a. The trade-off is the release artifacts will not yet be published. Although this is mitigated because the PR still requires manual approval and publishing a tag is a one-way door, to avoid confusion it would be good to only update the getting started version once the artifact is publicly available.

Limitations:

1. Similar to the existing update dependencies automation, the PR must be closed and reopened for workflow checks to run.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[sondavidb]

IMO it wouldn't be a bad idea to also include automation to update third-party licenses in this workflow. This will get run on patch versions and patch versions can potentially have different versions which could potentially have different licenses. Definitely not likely at all but a possibility that could be a problem if not caught IMO.

[austinvazquez]

IMO it wouldn't be a bad idea to also include automation to update third-party licenses in this workflow. This will get run on patch versions and patch versions can potentially have different versions which could potentially have different licenses. Definitely not likely at all but a possibility that could be a problem if not caught IMO.

@sondavidb take a look at #1248 which builds on this PR to achieve that goal.

[austinvazquez]

@pendo324, @sondavidb, I have added an assertion which is ran on pull request to the workflow and docs/getting-started.md to validate the update behaves correctly. Please take a look and lmk your thoughts.

[sondavidb]

LGTM, cool to automate another part of our release process

[austinvazquez]

@sondavidb, apologies I was doing some permissions testing in another branch and somehow mixed up the changes in this branch. Added permission contents: write back to this PR.