Release 14.8.0 into trunk

[oguzkocer]

Releasing new version 14.8.0.

What's Next

PR Author: Be sure to create and publish a GitHub Release pointing to trunk once this PR gets merged,
copy/pasting the following text as the GitHub Release's description:

### New Features

- Added `find_or_create_pull_request` action and `GithubHelper#find_pull_request`: returns the URL of the open Pull Request for a head branch, creating one only if none exists yet. Useful for "rolling" automations (e.g. a daily translations or dependency-update job) that force-push the same head branch on every run. [#733]
- Added `ContinuousBuildCodeFormatter`, which derives an Android Play Store `versionCode` for a "continuous trunk" release model as `(major * 10 + minor) * 10^build_digits + build_number` (default `build_digits: 6`). It encodes a high-cardinality, monotonically increasing build number (e.g. a Buildkite build number) that `DerivedBuildCodeFormatter` cannot hold, validates that `minor <= 9`, and guards against exceeding the Play Store's maximum `versionCode`. [#735]

[mokagio]

Taking this over. Thanks for your work @oguzkocer !