MAINT: Remove remaining uses of Python 3.6.

We missed a few first time around.

INSTALL.rst.txt

@@ -14,7 +14,7 @@ Prerequisites
 
 Building NumPy requires the following installed software:
 
-1) Python__ 3.6.x or newer.
+1) Python__ 3.7.x or newer.
 
    Please note that the Python development headers also need to be installed,
    e.g., on Debian/Ubuntu one needs to install both `python3` and

setup.py

@@ -26,8 +26,8 @@
 import warnings
 
 
-if sys.version_info[:2] < (3, 6):
-    raise RuntimeError("Python version >= 3.6 required.")
+if sys.version_info[:2] < (3, 7):
+    raise RuntimeError("Python version >= 3.7 required.")
 
 import builtins
 
@@ -40,7 +40,6 @@
 Programming Language :: C
 Programming Language :: Python
 Programming Language :: Python :: 3
-Programming Language :: Python :: 3.6
 Programming Language :: Python :: 3.7
 Programming Language :: Python :: 3.8
 Programming Language :: Python :: 3.9
@@ -473,7 +472,7 @@ def setup_package():
         platforms=["Windows", "Linux", "Solaris", "Mac OS-X", "Unix"],
         test_suite='pytest',
         cmdclass=cmdclass,
-        python_requires='>=3.6',
+        python_requires='>=3.7',
         zip_safe=False,
         entry_points={
             'console_scripts': f2py_cmds

test_requirements.txt

@@ -6,12 +6,10 @@ pytest==6.0.2
 pytz==2020.4
 pytest-cov==2.10.1
 pickle5; python_version == '3.7' and platform_python_implementation != 'PyPy'
-pickle5; python_version == '3.6' and platform_python_implementation != 'PyPy'
 # for numpy.random.test.test_extending
 cffi
 # For testing types. Notes on the restrictions:
 # - Mypy relies on C API features not present in PyPy
 # - Mypy doesn't currently work on Python 3.9
-# - Python 3.6 doesn't work because it doesn't understand py.typed
-mypy==0.790; platform_python_implementation != "PyPy" and python_version > "3.6"
+mypy==0.790; platform_python_implementation != "PyPy"
 typing_extensions

tox.ini

@@ -26,7 +26,7 @@
 
 [tox]
 envlist =
-  py36,py37,py38,
+  py37,py38,py39,
   py37-not-relaxed-strides
 
 [testenv]