chore: upgrade cross-spawn dev dependency (#689)

Fixes #662.

This did not upgrade automatically because the latest version of
`cdktf-cli` (which this package depends on for dev purposes) still [pins
to
7.3.0](https://github.com/hashicorp/terraform-cdk/blob/v0.20.10/packages/cdktf-cli/package.json#L52).

There is a pre-release of `cdktf-cli` which [already uses
7.0.6](https://github.com/hashicorp/terraform-cdk/blob/v0.21.0-pre.138/packages/cdktf-cli/package.json#L52)
so this resolution could be removed soon enough.

---------

Signed-off-by: epolon <epolon@amazon.com>
Signed-off-by: github-actions <github-actions@github.com>
Co-authored-by: github-actions <github-actions@github.com>

.projenrc.ts

@@ -50,6 +50,10 @@ releaseTask.exec(`npx projen ${integTask.name}`);
 const releaseWorkflow = project.tryFindObjectFile('.github/workflows/release.yml');
 releaseWorkflow!.addOverride('jobs.release.permissions.id-token', 'write');
 
+project.package.addField('resolutions', {
+  'cross-spawn': '^7.0.6',
+});
+
 project.synth();
 
 function jest(args: string) {