541: updates pypi metadata in setup file (#542)

Co-authored-by: Jacques Troussard <mm_sparrow@beeswaxnoneofyours.com>

setup.py

@@ -43,7 +43,7 @@ def readall(path):
     author_email="me@kennethreitz.com",
     url="https://github.com/requests/requests-oauthlib",
     packages=["requests_oauthlib", "requests_oauthlib.compliance_fixes"],
-    python_requires=">=3.4",
+    python_requires=">=3.7",
     install_requires=["oauthlib>=3.0.0", "requests>=2.0.0"],
     extras_require={"rsa": ["oauthlib[signedtoken]>=3.0.0"]},
     license="ISC",
@@ -54,9 +54,6 @@ def readall(path):
         "License :: OSI Approved :: BSD License",
         "Programming Language :: Python",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.4",
-        "Programming Language :: Python :: 3.5",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",