github/workflows: Add spell check to code formatting workflow.

Signed-off-by: Damien George <damien@micropython.org>

.github/workflows/code_formatting.yml

@@ -7,7 +7,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  build:
+  code-formatting:
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v3
@@ -18,3 +18,13 @@ jobs:
       run: source tools/ci.sh && ci_code_formatting_run
     - name: Check code formatting
       run: git diff --exit-code
+
+  code-spelling:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-python@v4
+    - name: Install packages
+      run: source tools/ci.sh && ci_code_spell_setup
+    - name: Run spell checker
+      run: source tools/ci.sh && ci_code_spell_run