Update terraform-linters/setup-tflint action to v6 (#77)

Author: renovate[bot]

.github/workflows/terraform.yml

@@ -94,7 +94,7 @@ jobs:
           key: tflint-${{ hashFiles(env.TFLINT_CONFIG_FILE_REL) }}
 
       - name: Setup TFLint
-        uses: terraform-linters/setup-tflint@v5
+        uses: terraform-linters/setup-tflint@v6
         if: success() || failure()
 
       - name: Init TFLint