Clear cache workflow (#2703)

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### What

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/2703) (if
applicable)

- [PR Build Summary](https://build.rerun.io/pr/2703)
- [Docs preview](https://rerun.io/preview/pr%3Ajan%2Fclear-cache/docs)
- [Examples
preview](https://rerun.io/preview/pr%3Ajan%2Fclear-cache/examples)

.github/workflows/clear_cache.yml

@@ -0,0 +1,29 @@
+name: Clear cache
+
+on:
+  workflow_dispatch:
+
+permissions:
+  actions: write
+
+jobs:
+  clear-cache:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clear cache
+        uses: actions/github-script@v6
+        with:
+          script: |
+            const caches = await github.rest.actions.getActionsCacheList({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+            });
+            console.log(`clearing ${caches.total_count} cache entries`);
+            for (const cache of caches.data.actions_caches) {
+              console.log(`clearing ${cache.key}`);
+              github.rest.actions.deleteActionsCacheById({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                cache_id: cache.id,
+              }).then(() => console.log(`cleared ${cache.key}`));
+            }