ci: Clean up some disk space before running tests

Running against a `system-postgres` can cause the disk to fill
up. Cleaning up some more space hopefully makes them work
again. Technically the postgres DBs are deleted after the test,
however that may be delayed, and many nodes in parallel will cause the
disk to fill up.

Author: cdecker

.github/workflows/ci.yaml

@@ -310,6 +310,26 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Check disk space pre-cleanup
+        run: df -h
+      - name: Free up disk space
+        # We need more space than GHA usually provides when testing
+        # against the `postgres` service. This step frees some space
+        # on the volume containing tools, in the hope of freeing
+        # enough space for postgres tests to succeed.
+        uses: jlumbroso/free-disk-space@main
+        with:
+          # Enable all cleanup options
+          tool-cache: true
+          android: true
+          dotnet: true
+          haskell: true
+          swift: true
+          golang: true
+          php: true
+      - name: Check disk space pre-cleanup
+        run: df -h
+        
       - name: Set up Python 3.10
         uses: actions/setup-python@v5
         with:

contrib/pyln-testing/pyln/testing/db.py

@@ -113,6 +113,7 @@ def stop(self):
         cur = conn.cursor()
         cur.execute("DROP DATABASE {};".format(self.dbname))
         cur.close()
+        conn.close()
 
     def wipe_db(self):
         cur = self.conn.cursor()