chore(deps): bump actions/checkout from v2 to v2.3.0 (#1613)

Bumps [actions/checkout](https://github.com/actions/checkout) from v2 to v2.3.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/master/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2...b4483adec309c0d01a5435c5e24eb40de5773ad9)

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

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

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.0
         with:
           fetch-depth: 0
       -

.github/workflows/docs.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.0
       -
         name: build
         run: |

.github/workflows/gosum.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.0
       -
         name: Set up Go
         uses: actions/setup-go@v2