Pin parse version to >=1.8.4

parse 1.8.4 is the first version of the `case_sensitive` argument introduced. We had this exact issue where this code block failed because the installed _parse_ version was 1.6.x
https://github.com/olirice/alembic_utils/blob/master/src/alembic_utils/pg_function.py#L43

https://pypi.org/project/parse/1.8.4/
`>>> parse('SPAM', 'spam', case_sensitive=True) is None`

Author: dimitris-flyr

setup.py

@@ -37,7 +37,7 @@ def get_version(package):
         "alembic>=1.5.7",
         "flupy",
         "sqlalchemy>=1.3.0",
-        "parse",
+        "parse>=1.8.4",
         "typing_extensions",
     ],
     extras_require={