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/main.yml

@@ -13,7 +13,7 @@ jobs:
     name: Tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
       - uses: actions/setup-node@v2
         with:
           node-version: 12.x
@@ -41,7 +41,7 @@ jobs:
       #         Checkout        #
       ###########################
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
         with:
           lfs: true
 
@@ -82,7 +82,7 @@ jobs:
       ###########################
       #         Checkout        #
       ###########################
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           lfs: true
 
@@ -129,7 +129,7 @@ jobs:
       ###########################
       #         Checkout        #
       ###########################
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           lfs: true
 
@@ -176,7 +176,7 @@ jobs:
       ###########################
       #         Checkout        #
       ###########################
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           lfs: true
 
@@ -223,7 +223,7 @@ jobs:
       ###########################
       #         Checkout        #
       ###########################
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           lfs: true