Bump actions/checkout from 2 to 2.3.4 (hugo-toha#64)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v2.3.4)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

.github/workflows/deploy-site.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
     # checkout to the commit that has been pushed
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.4
       with:
         submodules: true  # Fetch Hugo themes (true OR recursive)
         fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod

.github/workflows/html-proof.yaml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
     # checkout to the commit that has been pushed
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.4
       with:
         submodules: true  # Fetch Hugo themes (true OR recursive)
         fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod

.github/workflows/md-link-check.yaml

@@ -8,6 +8,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     # checkout to latest commit
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2.3.4
     # run markdown linter
     - uses: gaurav-nelson/github-action-markdown-link-check@v1

.github/workflows/percy.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.3
+        uses: actions/checkout@v2.3.4
         with:
           submodules: true  # Fetch Hugo themes (true OR recursive)
           fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod