In a pull request, GITHUB_SHA is set to the "last merge commit on the GITHUB_REF branch".
This isn't the correct value to use when generating a dependency graph.
This changes to use the value of `pull_request.head.sha`, which is the correct
value for a dependency graph.

Fixes #882

Signed-off-by: Benoit Pierre <benoit.pierre@gmail.com>

### Github Action updates

Updates `gradle/gradle-build-action` from 2.8.0 to 2.8.1

### NPM updates

Updates `@octokit/webhooks-types` from 7.3.0 to 7.3.1
- [Release notes](https://github.com/octokit/webhooks/releases)
- [Commits](octokit/webhooks@v7.3.0...v7.3.1)

Updates `@typescript-eslint/parser` from 6.7.2 to 6.7.3
- [Release notes](https://github.com/typescript-eslint/typescript-eslint/releases)
- [Changelog](https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/parser/CHANGELOG.md)
- [Commits](https://github.com/typescript-eslint/typescript-eslint/commits/v6.7.3/packages/parser)

Updates `eslint` from 8.49.0 to 8.50.0
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/main/CHANGELOG.md)
- [Commits](eslint/eslint@v8.49.0...v8.50.0)

- Allow environment variables to be overridden by system properties in dependency-graph initscript
- Set `GITHUB_DEPENDENCY_GRAPH_ENABLED=false` when executing Gradle for cache cleanup

When using 'download-and-submit' for dependency graphs, we now run the
submission immediately instead of waiting until the post-action.
This allows a single job to both submit the graph and run the dependency
review action.

A common issue when submitting a dependency graph is that the required
'contents: write' permission is not set.
We now catch any dependency submission failure and inform the user to check
that the required permissions are available.