Switch to using setuptools_scm for versioning

This MR is a possible alternative to !1118 (closed) and uses setuptools_scm instead of versioneer.

The most notable change is the inclusion of pyproject.toml which, as of PEP 518, is the recommended way to manage build dependencies and is also used to configure setuptools_scm.

One thing to note with this approach is that when using an editable install (pip install -e .) the version is only updated when the module is installed rather than every time it is imported. I'm not sure how this compares to versioneer.

• Closes #577 (closed)

bilby/core/utils/log.py

 import logging
-import os
 from pathlib import Path
 import sys
 
@@ -60,13 +59,8 @@ def setup_logger(outdir='.', label=None, log_level='INFO', print_version=False):
 
 
 def get_version_information():
-    version_file = os.path.join(
-        os.path.dirname(os.path.dirname(os.path.dirname(__file__))), '.version')
-    try:
-        with open(version_file, 'r') as f:
-            return f.readline().rstrip()
-    except EnvironmentError:
-        print("No version information file '.version' found")
+    from bilby import __version__
+    return __version__
 
 
 def loaded_modules_dict():