implement first pass at cached image data source (#3)

implements envbuilder_cached_image data source

.github/workflows/test.yml

@@ -65,11 +65,12 @@ jobs:
       matrix:
         # list whatever Terraform versions here you would like to support
         terraform:
-          - '1.0.*'
-          - '1.1.*'
-          - '1.2.*'
-          - '1.3.*'
-          - '1.4.*'
+          # TODO: test with more terraform versions. For now, testing with latest.
+          # - "1.5.*"
+          # - "1.6.*"
+          # - "1.7.*"
+          # - "1.8.*"
+          - "1.9.*"
     steps:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
       - uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
@@ -81,6 +82,7 @@ jobs:
           terraform_version: ${{ matrix.terraform }}
           terraform_wrapper: false
       - run: go mod download
+      - run: make test-registry
       - env:
           TF_ACC: "1"
         run: go test -v -cover ./internal/provider/