chore(deps): update actions/checkout action to v2.4.2 (#90)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/doc-publish.yml

@@ -9,7 +9,7 @@ jobs:
     name: Build Docs
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/[email protected].0
+      - uses: actions/[email protected].2
       - name: Install Toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1
         with: