ci: build: clean up space before ci build

clean up the docker container before we run ci buildswq

Signed-off-by: Dhruva Gole <d-gole@ti.com>

Author: DhruvaG2000

.github/workflows/build.yml

@@ -3,6 +3,14 @@ name: Build
 on: [push, pull_request]
 
 jobs:
+  cleanup:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cleanup Docker images and containers
+        run: |
+          docker system prune -af
+          docker volume prune -f
+
   build:
     runs-on: ubuntu-latest
     container: zephyrprojectrtos/ci:latest