Set proper lower bound for portalocker dependency, drop packaging dependency

msal_extensions/cache_lock.py

@@ -6,7 +6,6 @@
 import logging
 
 import portalocker
-from packaging.version import Version
 
 
 logger = logging.getLogger(__name__)
@@ -19,9 +18,6 @@ class CrossPlatLock(object):
     """
     def __init__(self, lockfile_path):
         self._lockpath = lockfile_path
-        # Support for passing through arguments to the open syscall was added in v1.4.0
-        open_kwargs = ({'buffering': 0}
-            if Version(portalocker.__version__) >= Version("1.4.0") else {})
         self._lock = portalocker.Lock(
             lockfile_path,
             mode='wb+',
@@ -30,7 +26,10 @@ def __init__(self, lockfile_path):
             # More information here:
             # https://docs.python.org/3/library/fcntl.html#fcntl.lockf
             flags=portalocker.LOCK_EX | portalocker.LOCK_NB,
-            **open_kwargs)
+            # Support for passing through arguments to the open syscall
+            # was added in Portalocker v1.4.0 (2019-02-11).
+            buffering=0,
+        )
 
     def _try_to_create_lock_file(self):
         timeout = 5

setup.py

@@ -20,17 +20,10 @@
     python_requires=">=3.7",
     install_requires=[
         'msal>=0.4.1,<2.0.0',
-
-        "portalocker<3,>=1.0;platform_system!='Windows'",
-        "portalocker<3,>=1.6;platform_system=='Windows'",
+        'portalocker<3,>=1.4',
 
         ## We choose to NOT define a hard dependency on this.
         # "pygobject>=3,<4;platform_system=='Linux'",
-
-        # Packaging package uses YY.N versioning so we have no upperbound to pin.
-        # Neither do we need lowerbound because its `Version` API existed since its first release
-        # https://github.com/pypa/packaging/blame/14.0/packaging/version.py
-        'packaging',
     ],
     tests_require=['pytest'],
 )