Update actions/checkout requirement to v2.3.4

Updates the requirements on [actions/checkout](https://github.com/actions/checkout) to permit the latest version.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/commits/5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f)

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

Author: dependabot[bot]

.github/workflows/graalvm.yml

@@ -11,7 +11,7 @@ jobs:
   macos:
     runs-on: macos-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -47,7 +47,7 @@ jobs:
   linux:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -87,7 +87,7 @@ jobs:
     env:
       VCVARS_BAT: C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -121,7 +121,7 @@ jobs:
     needs: [macos, linux, windows]
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     outputs:
       new_version: ${{ steps.tag.outputs.new_version }}
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2.3.4
       with:
         # fetch entire history to analyze commits since last tag
         fetch-depth: 0
@@ -24,7 +24,7 @@ jobs:
     runs-on: macos-latest
     needs: version
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -61,7 +61,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: version
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -102,7 +102,7 @@ jobs:
     env:
       VCVARS_BAT: C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'
@@ -136,7 +136,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [version, macos, linux, windows]
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - name: Download all workflow run artifacts
       uses: actions/download-artifact@v2
       with:
@@ -193,7 +193,7 @@ jobs:
     needs: [version, release]
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: actions/setup-java@v1
       with:
         java-version: '11'