Bump subosito/flutter-action from 2.12.0 to 2.15.0 (#603)

Bumps [subosito/flutter-action](https://github.com/subosito/flutter-action) from 2.12.0 to 2.15.0.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/subosito/flutter-action/releases">subosito/flutter-action's releases</a>.</em></p>
<blockquote>
<h2>v2.15.0</h2>
<p>Hi! I'm <a href="https://github.com/bartekpacia/">Bartek</a> and I'm a new maintainer of this action. I promise to take good care of it.</p>
<p>This release introduces the <code>flutter-version-file</code> option, which lets you easily centralize Flutter version in a single place � your pubspec.yaml file:</p>
<p>You can use it like this:</p>
<pre lang="yaml"><code>steps:
  - name: Clone repository
    uses: actions/checkout@v4
  - name: Set up Flutter
    uses: subosito/flutter-action@v2
    with:
      channel: stable
      flutter-version-file: pubspec.yaml # path to pubspec.yaml
</code></pre>
<p>Please note that for this to work, you need to specify exact Flutter version in pubspec.yaml:</p>
<pre lang="yaml"><code>environment:
  dart: &quot;&gt;=3.3.0 &lt;4.0.0&quot;
  flutter: 3.19.0 # This must be exact! No ranges allowed.
</code></pre>
<p>Apart from that, some minor README updates and code cleanup were performed.</p>
<h2>v2.14.0</h2>
<p>No release notes provided.</p>
<h2>v2.13.0</h2>
<p>No release notes provided.</p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/subosito/flutter-action/commit/3d804929922b667a63a229bc59037807f969e885"><code>3d80492</code></a> update README (<a href="https://redirect.github.com/subosito/flutter-action/issues/291">#291</a>)</li>
<li><a href="https://github.com/subosito/flutter-action/commit/0ef13f12a53071c2362b0f884ad917692ff8cbc5"><code>0ef13f1</code></a> Add <code>flutter-version-file</code> (<a href="https://redirect.github.com/subosito/flutter-action/issues/290">#290</a>)</li>
<li><a href="https://github.com/subosito/flutter-action/commit/7564de34b3630708aa08807092c5ddbf4f6e0a7d"><code>7564de3</code></a> Merge pull request <a href="https://redirect.github.com/subosito/flutter-action/issues/288">#288</a> from subosito/chore/action_yaml_refactor</li>
<li><a href="https://github.com/subosito/flutter-action/commit/2b3ab6c7da1a24f4e4589856c0609a28c2393e7c"><code>2b3ab6c</code></a> convert some if-statements to be POSIX-compatible</li>
<li><a href="https://github.com/subosito/flutter-action/commit/49cd17165c0e40bec4f918edd05e5e1e5e1938c9"><code>49cd171</code></a> split longer lines</li>
<li><a href="https://github.com/subosito/flutter-action/commit/cf12a399890e96433bcc3bcd58cf894cb9f36162"><code>cf12a39</code></a> Merge pull request <a href="https://redirect.github.com/subosito/flutter-action/issues/287">#287</a> from subosito/minor</li>
<li><a href="https://github.com/subosito/flutter-action/commit/cea4cf68a127f658cd53308d618402e7e0bc4e52"><code>cea4cf6</code></a> workflow.yaml: minor fix</li>
<li><a href="https://github.com/subosito/flutter-action/commit/043862d93028d14cac42b28d5eecbc99aaef64f4"><code>043862d</code></a> Merge pull request <a href="https://redirect.github.com/subosito/flutter-action/issues/286">#286</a> from subosito/format</li>
<li><a href="https://github.com/subosito/flutter-action/commit/e70699e140cf8f07d411bafa936437de5a7560e1"><code>e70699e</code></a> file renames</li>
<li><a href="https://github.com/subosito/flutter-action/commit/766e0c11bc704f670072f0bb23cd50d33e7be3cd"><code>766e0c1</code></a> minor readme format update</li>
<li>Additional commits viewable in <a href="https://github.com/subosito/flutter-action/compare/2783a3f08e1baf891508463f8c6653c258246225...3d804929922b667a63a229bc59037807f969e885">compare view</a></li>
</ul>
</details>
<br />

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</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@2783a3f08e1baf891508463f8c6653c258246225
+        uses: subosito/flutter-action@3d804929922b667a63a229bc59037807f969e885
         with:
           channel: 'beta'