remove 1.20

some weird bug where github CI always uses 1.21, so no point

.github/workflows/run_tests.yml

@@ -6,7 +6,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        golang-version: ['1.20', '1.21']
+        golang-version: ['1.21']
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4

README.md

@@ -194,7 +194,7 @@ Recommended: Install any version via go install:
 go install github.com/transcend-io/terragrunt-atlantis-config@v1.21.0
 ```
 
-This module officially supports golang versions v1.20, and v1.21, tested on Github with each build. 
+This module officially supports golang version v1.21, tested on Github with each build. 
 This module also officially supports both Windows and Nix-based file formats, tested on Github with each build. 
 
 Usage Examples (see below sections for all options):