Try to free up space on github actions workers. (#5342)

This should hopefully mitigate the risk of `no space left on device`
that sometimes happens

Author: lihaoyi

.github/actions/post-build-selective/action.yml

@@ -15,6 +15,16 @@ inputs:
 runs:
   using: "composite"
   steps:
+    # Try to free up some space on the github actions runners by deleting things we
+    # don't care about. Truncate the output using `head` so we can still see some output,
+    # but not so much it floods the logs
+    - run: head -n100 <(rm -rfv /usr/local/lib/android)
+      shell: bash
+    - run: head -n100 <(rm -rfv /opt/ghc)
+      shell: bash
+    - run: head -n100 <(rm -rfv /usr/local/.ghcup)
+      shell: bash
+
     - uses: actions/setup-node@v4
       with: { node-version: '22' }