Use correct PEP 440 fallback version

Reference: #86
Signed-off-by: Ayan Sinha Mahapatra <ayansmahapatra@gmail.com>

Author: AyanSinhaMahapatra

pyproject.toml

@@ -5,7 +5,7 @@ build-backend = "setuptools.build_meta"
 [tool.setuptools_scm]
 # this is used populated when creating a git archive
 # and when there is .git dir and/or there is no git installed
-fallback_version = "9999.$Format:%h-%cs$"
+fallback_version = "9999+$Format:%h$"
 
 [tool.pytest.ini_options]
 norecursedirs = [