Bump actions/checkout from v2 to v3

Author: parkerbxyz

Diff for: .github/workflows/jekyll.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
 
     # Node-specific steps
     - name: Install node modules