Build nim-waku if the binary cannot be executed

.github/workflows/ci.yml

@@ -35,9 +35,8 @@ jobs:
         # This would have been done part of npm pretest but it gives better
         # visibility in the CI if done as a separate step
       - name: Build wakunode2
-        if: steps.cache-nim-waku.outputs.cache-hit != 'true'
         shell: bash
-        run: cd nim-waku && make wakunode2
+        run: cd nim-waku && ./build/wakunode2 --help || make wakunode2
 
       - name: Ensure wakunode2 is ready
         shell: bash