chore(@aws-cdk-testing/cli-integ): add sinon dep

Add an explicit dependency on a version of sinon that we depend on in
other packages. This version is what is used by `aws-cdk-lib` currently.
This fixes an issue that occurs currently when installing
@aws-cdk-testing/cli-integ in a directory that is not a git repository
as described [in this issue](sinonjs/sinon#2557).

This doesn't occur during local development because yarn dedupes sinon
to a version that intersects with the peerDep range taken by
`ts-mock-imports` and versions depended on by other packages, such as
`aws-cdk-lib`.

packages/@aws-cdk-testing/cli-integ/package.json

@@ -49,6 +49,7 @@
     "npm": "^8.19.4",
     "p-queue": "^6.6.2",
     "semver": "^7.5.4",
+    "sinon": "^9.2.4",
     "ts-mock-imports": "^1.3.8",
     "yaml": "1.10.2",
     "yargs": "^17.7.2"