ci: add cache for tf-lint (#100)

This pull request includes an update to the CI workflow configuration to
improve efficiency by caching TFLint plugins.

*
[`.github/workflows/ci.yml`](diffhunk://#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fR110-R114):
Added `actions/cache@v4` to cache TFLint plugins, which helps in
reducing the time taken to set up TFLint during CI runs.

Author: babinskiy

.github/workflows/ci.yml

@@ -107,6 +107,11 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        with:
+          path: ~/.tflint.d/plugins
+          key: tflint-${{ runner.os }}-${{ hashFiles('.tflint.hcl') }}
+
       - uses: terraform-linters/setup-tflint@v4
         with:
           tflint_version: "latest"