.github/workflows: Test on Terraform 1.4.* versions (#272)

Reference: https://github.com/hashicorp/terraform-providers-devex-internal/issues/139

Author: bflad

.github/workflows/ci-go.yml

@@ -63,6 +63,7 @@ jobs:
           - '1.1.*'
           - '1.2.*'
           - '1.3.*'
+          - '1.4.*'
   terraform-provider-corner-tfprotov6:
     defaults:
       run:
@@ -99,6 +100,7 @@ jobs:
           - '1.1.*'
           - '1.2.*'
           - '1.3.*'
+          - '1.4.*'
   test:
     name: test (Go v${{ matrix.go-version }})
     runs-on: ubuntu-latest