chore!: Bump version to 0.2.0

BREAKING CHANGE: The schema of the `json` export has changed.

Previously...
```json
{
  "./path": {
    "author": 1234
  }
}
```

Now...
```
{
  "./path": {
    "author": {
      "lines": 1234,
      "license": "MIT" // Optional key
    }
  }
}
```

pyproject.toml

@@ -6,7 +6,7 @@
 
 [tool.poetry]
 name = "git-authorship"
-version = "0.1.5"
+version = "0.2.0"
 description = "Interactive reports showing who wrote each line of code in your git repository."
 authors = ["Joseph Hale <[email protected]>"]
 license = "MPL-2.0"