Merge pull request #236 from mathause/update_py37

update mentions of py3.7

Author: kafitzgerald

doc/source/installation.rst

@@ -4,7 +4,7 @@ Installation
 Required Dependencies
 ----------------------
 
-    - Python 2.7, 3.4, or 3.5+
+    - Python 3.9+
     - numpy (1.11 or later; 1.14 required to build on Windows)
     - wrapt (1.10 or later)
     - setuptools (38.0 or later) 

doc/source/tutorials/wrf_workshop_2019.rst

@@ -82,7 +82,7 @@ Step 2: Download Miniconda
 ----------------------------
 
 For this tutorial, you will need to download and install Miniconda.  We are 
-going to use Python 3.7, but it will also work with Python 2.7. 
+going to use Python 3.7, but it will also work with Python 2.7.
 
 Please use the appropriate link below to download Miniconda for your operating 
 system. 

setup.py

@@ -96,7 +96,7 @@
               "plotting", "plots", "meteorology", "nwp",
               "numerical weather prediction", "diagnostic",
               "science", "numpy"],
-    python_requires='>=3.7, <3.12',
+    python_requires='>=3.9, <3.12',
     install_requires=requirements,
     classifiers=["Development Status :: 5 - Production/Stable",
                  "Intended Audience :: Science/Research",