Increase coverage

[pflorek]

Have for each construct at least a very simple test

For example matching a snapshot:

https://github.com/pepperize/cdk-github/blob/main/test/github-custom-resource.test.ts

describe("GithubCustomResource", () => {
 it("Should match snapshot", () => {
 // Given
 const stack = new Stack();
 new GithubCustomResource(stack, "CR", {
 // ...
 });
 
 // When
 const template = Template.fromStack(stack);
 
 // Then
 expect(template).toMatchSnapshot();
 });
});