Bump actions/cache from 6.0.0 to 6.1.0 (#10023)

[//]: # (dependabot-start)
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[//]: # (dependabot-end)

Bumps [actions/cache](https://github.com/actions/cache) from 6.0.0 to
6.1.0.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/actions/cache/releases">actions/cache's
releases</a>.</em></p>
<blockquote>
<h2>v6.1.0</h2>
<h2>What's Changed</h2>
<ul>
<li>Bump <code>@​actions/cache</code> to v6.1.0 - handle read-only cache
access by <a
href="https://github.com/jasongin"><code>@​jasongin</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1768">actions/cache#1768</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/actions/cache/compare/v6...v6.1.0">https://github.com/actions/cache/compare/v6...v6.1.0</a></p>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/actions/cache/blob/main/RELEASES.md">actions/cache's
changelog</a>.</em></p>
<blockquote>
<h3>6.1.0</h3>
<ul>
<li>Bump <code>@actions/cache</code> to v6.1.0 to pick up <a
href="https://redirect.github.com/actions/toolkit/pull/2435">actions/toolkit#2435
Handle cache write error due to read-only token</a></li>
<li>Switch redundant &quot;Cache save failed&quot; warning to debug log
in save-only</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="55cc834586"><code>55cc834</code></a>
Merge pull request <a
href="https://redirect.github.com/actions/cache/issues/1768">#1768</a>
from jasongin/readonly-cache</li>
<li><a
href="d8cd72f230"><code>d8cd72f</code></a>
Bump <code>@​actions/cache</code> to v6.1.0 - handle cache write error
due to RO token</li>
<li>See full diff in <a
href="https://github.com/actions/cache/compare/v6.0.0...v6.1.0">compare
view</a></li>
</ul>
</details>
<br />


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.github/workflows/build-z3-cache.yml

@@ -45,7 +45,7 @@ jobs:
 
       - name: Restore or create cache
         id: cache-z3
-        uses: actions/cache@v6.0.0
+        uses: actions/cache@v6.1.0
         with:
           path: |
             build/z3

.github/workflows/ocaml.yaml

@@ -21,7 +21,7 @@ jobs:
 
       # Cache ccache (shared across runs)
       - name: Cache ccache
-        uses: actions/cache@v6.0.0
+        uses: actions/cache@v6.1.0
         with:
           path: ~/.ccache
           key: ${{ runner.os }}-ccache-${{ github.sha }}
@@ -30,7 +30,7 @@ jobs:
 
       # Cache opam (compiler + packages)
       - name: Cache opam
-        uses: actions/cache@v6.0.0
+        uses: actions/cache@v6.1.0
         with:
           path: ~/.opam
           key: ${{ runner.os }}-opam-${{ matrix.ocaml-version }}-${{ github.sha }}