serverless-esbuild: non-semver references excluded by yarn packager

This demonstrates an issue with the yarn packager in serverless-esbuild, where github-referenced dependencies are not included in the packaged sls node_modules. floydspace/serverless-esbuild#477

Staps

1. Run yarn install
2. Note that node_modules/@identity.com/package.json imports a @metacask lib using a github reference:

 "@metacask/kyc-token-client": "git+ssh://[email protected]/mcask/kyc-token-client.git#0.3.2",

3. Run yarn sls package
4. Unzip the function .serverless/test.zip
5. Note that the packages node_modules has no @metacask/kyc-token-client dependency.