ci: add slither static analysis

Author: varunsrin

.github/workflows/ci.yml

@@ -61,3 +61,9 @@ jobs:
 
       - name: Check Forge gas snapshot
         run: forge snapshot --check
+
+      - name: Run Slither
+        uses: crytic/slither-action@v0.1.1
+        with:
+          ignore-compile: true
+          target: "src/"