chore!: change default Terraform version to 1.9.0 (#190)

This PR increases the default version of Terraform used from `1.8.5` to
version `1.9.0`.
This is considered a breaking change because anyone who does not
manually specify a `terraformVersion` in their action configuration will
automatically start using the new version.
 
Unfortunately, not everything can be automated, and the following steps
need to be completed manually:
 
- [x] Update the _Terraform Version_ to `1.9.0` in the TFC web UI for
the
[cdk-action-testing](https://app.terraform.io/app/cdktf/workspaces/cdk-action-testing/settings/general)
workspace
 
Please complete the above steps and then mark this PR as ready for
review to rerun the checks. Thanks!

Signed-off-by: team-tf-cdk <[email protected]>

.projenrc.ts

@@ -29,7 +29,7 @@ const inputs = {
   },
   terraformVersion: {
     description: "The version of Terraform to use",
-    default: "1.8.5",
+    default: "1.9.0",
     required: false,
     type: "string",
   },

README.md

@@ -8,7 +8,7 @@ The Terraform CDK GitHub Action allows you to run CDKTF as part of your CI/CD wo
 | parameter | description | required | default |
 | --- | --- | --- | --- |
 | cdktfVersion | The version of CDKTF to use | `false` | 0.20.7 |
-| terraformVersion | The version of Terraform to use | `false` | 1.8.5 |
+| terraformVersion | The version of Terraform to use | `false` | 1.9.0 |
 | workingDirectory | The directory to use for the project | `false` | ./ |
 | mode | What action to take: `synth-only` runs only the synthesis, `plan-only` only runs a plan, `auto-approve-apply` runs a plan and then performs an apply, `auto-approve-destroy` runs a plan and then performs a destroy | `true` |  |
 | stackName | The stack to run / plan, only required when the mode is `plan-only` or `plan-and-apply` | `false` |  |
@@ -58,10 +58,10 @@ jobs:
         run: yarn test
 
       - name: Run Terraform CDK
-        uses: hashicorp/terraform-cdk-action@v4
+        uses: hashicorp/terraform-cdk-action@v5
         with:
           cdktfVersion: 0.20.7
-          terraformVersion: 1.8.5
+          terraformVersion: 1.9.0
           mode: plan-only
           stackName: my-stack
           terraformCloudToken: ${{ secrets.TF_API_TOKEN }}
@@ -106,10 +106,10 @@ jobs:
         run: yarn test
 
       - name: Run Terraform CDK
-        uses: hashicorp/terraform-cdk-action@v4
+        uses: hashicorp/terraform-cdk-action@v5
         with:
           cdktfVersion: 0.20.7
-          terraformVersion: 1.8.5
+          terraformVersion: 1.9.0
           mode: auto-approve-apply
           stackName: my-stack
           terraformCloudToken: ${{ secrets.TF_API_TOKEN }}
@@ -150,10 +150,10 @@ jobs:
         run: yarn test
 
       - name: Test the synth
-        uses: hashicorp/terraform-cdk-action@v4
+        uses: hashicorp/terraform-cdk-action@v5
         with:
           cdktfVersion: 0.20.7
-          terraformVersion: 1.8.5
+          terraformVersion: 1.9.0
           mode: synth-only
           stackName: my-stack
 ```