ci: separate job for semgrep (#56580)

.github/workflows/linters.yml

@@ -20,6 +20,18 @@ jobs:
       - name: Install and Run Pre-commit
         uses: pre-commit/action@v3.0.1
 
+  semgrep:
+    name: semgrep
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+          cache: pip
+
       - name: Download Semgrep rules
         run: git clone --depth 1 https://github.com/frappe/semgrep-rules.git frappe-semgrep-rules