feat: add terraform-git service account for woodpecker CI (#189)

## Summary
- Add ServiceAccount terraform-git in woodpecker namespace for terraform-git CI pipelines
- Add to kustomization.yaml

## Test plan
- [ ] Verify ArgoCD syncs the new service account
- [ ] Verify woodpecker CI can use the service account

Reviewed-on: #189
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

apps/base/woodpecker/kustomization.yaml

@@ -6,6 +6,7 @@ resources:
   - namespace.yaml
   - cnpg_cluster.yaml
   - cnpg_pooler.yaml
+  - serviceaccount_terraform_git.yaml
   - serviceaccount_terraform_vault.yaml
   - vaultauth.yaml
   - vaultstaticsecret.yaml