Fix pylaprof-merge setup

Unfortunately the 'scripts' feature of setuptools[^1] hasn't made its
way into Poetry yet (it has already been merged[^2] but not yet
released).

For the moment we'll need to keep the scripts directory inside
pylaprof (although I wanted to avoid it) and install pylaprof-merge
as an entry point[^3].

[^1]: https://python-packaging.readthedocs.io/en/latest/command-line-scripts.html#the-scripts-keyword-argument
[^2]: python-poetry/poetry-core#40
[^3]: https://python-packaging.readthedocs.io/en/latest/command-line-scripts.html#the-console-scripts-entry-point

pyproject.toml

@@ -26,7 +26,7 @@ boto3 = "^1.20.6"
 moto = {extras = ["s3"], version = "^2.2.15"}
 
 [tool.poetry.scripts]
-pylaprof-merge = "scripts.merge:main"
+pylaprof-merge = "pylaprof.scripts.merge:main"
 
 [tool.coverage.run]
 branch = true