Dependabot PRs that update a **single** dependency include version details in the commit message introduction, e.g.,
> "Bumps `<dependency>` from `<prevVersion>` to `<newVersion>`"
This is the format generated by the [`commit_message_intro`](https://github.com/dependabot/dependabot-core/blob/cc4b4eaade37da0a19e0897e6897bab613064e74/common/lib/dependabot/pull_request_creator/message_builder.rb#L320-L325) method in Dependabot Core.

However, when **multiple dependencies** are updated in a single PR, this format isn't used consistently, which limits the action’s ability to extract accurate version information.

This change improves version parsing for multi-dependency PRs by introducing two additional detection strategies:

1. **YAML metadata parsing**
   Dependabot includes a YAML block in the commit message with structured details for each updated dependency:
   ```yaml
   updated-dependencies:
   - dependency-name: commons-codec:commons-codec
     dependency-version: 1.18.0
     dependency-type: direct:production
     update-type: version-update:semver-minor
     dependency-group: non-breaking
   ```
   This is the most reliable and stable source for the **new** version of each dependency, though it does **not** include the previous version.

2. **Metadata links parsing**
   In multi-dependency updates, Dependabot also appends “metadata links” with a format like:
   > "Updates `<dependencyName>` from `<prevVersion>` to `<newVersion>`"
     These lines are generated bythe [`metadata_links`](https://github.com/dependabot/dependabot-core/blob/cc4b4eaade37da0a19e0897e6897bab613064e74/common/lib/dependabot/pull_request_creator/message_builder.rb#L664-L678) method and provide **both** the old and new versions.

By combining these sources, the action now supports version parsing for PRs with multiple updated dependencies—broadening its coverage and improving reliability.

Closes dependabot#402