Bump actions/checkout from 2 to 2.3.4

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](https://github.com/actions/checkout/compare/v2...v2.3.4)

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

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
 
       - name: Docker meta
         id: docker_meta

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
 
       - name: Docker meta
         id: docker_meta