Bump subosito/flutter-action from 2.11.0 to 2.12.0 (#569)

Bumps [subosito/flutter-action](https://github.com/subosito/flutter-action) from 2.11.0 to 2.12.0.
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/subosito/flutter-action/commit/2783a3f08e1baf891508463f8c6653c258246225"><code>2783a3f</code></a> ensure setup.sh executable; fixes <a href="https://redirect.github.com/subosito/flutter-action/issues/245">#245</a></li>
<li><a href="https://github.com/subosito/flutter-action/commit/c33c37022b3aac486cc5e7aea5c7f6b8b0f421e1"><code>c33c370</code></a> Extract to a temporary location to enable moving of flutter folder. (<a href="https://redirect.github.com/subosito/flutter-action/issues/227">#227</a>)</li>
<li>See full diff in <a href="https://github.com/subosito/flutter-action/compare/cc97e1648fff6ca5cc647fa67f47e70f7895510b...2783a3f08e1baf891508463f8c6653c258246225">compare view</a></li>
</ul>
</details>
<br />

[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=subosito/flutter-action&package-manager=github_actions&previous-version=2.11.0&new-version=2.12.0)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`.

---

<details>
<summary>Dependabot commands and options</summary>
<br />

You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it
- `@dependabot merge` will merge this PR after your CI passes on it
- `@dependabot squash and merge` will squash and merge this PR after your CI passes on it
- `@dependabot cancel merge` will cancel a previously requested merge and block automerging
- `@dependabot reopen` will reopen this PR if it is closed
- `@dependabot close` will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
- `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency
- `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

</details>

.github/workflows/flutter_markdown.yaml

@@ -32,7 +32,7 @@ jobs:
 
       # Install the Flutter SDK using the subosito/flutter-action GitHub action.
       - name: install the flutter sdk
-        uses: subosito/flutter-action@cc97e1648fff6ca5cc647fa67f47e70f7895510b
+        uses: subosito/flutter-action@2783a3f08e1baf891508463f8c6653c258246225
         with:
           channel: 'beta'