Update setup.cfg and release builds to show python 3.9 support

Author: dihm

.github/workflows/release.yml

@@ -42,18 +42,22 @@ jobs:
     strategy:
       matrix:
         include:
+          - { os: ubuntu-latest,   python: 3.9,  arch: x64 }
           - { os: ubuntu-latest,   python: 3.8,  arch: x64 }
           - { os: ubuntu-latest,   python: 3.7,  arch: x64 }
           - { os: ubuntu-latest,   python: 3.6,  arch: x64 }
 
+          - { os: macos-latest,    python: 3.9,  arch: x64 }
           - { os: macos-latest,    python: 3.8,  arch: x64 }
           - { os: macos-latest,    python: 3.7,  arch: x64 }
           - { os: macos-latest,    python: 3.6,  arch: x64 }
 
+          - { os: windows-latest,  python: 3.9,  arch: x64 }
           - { os: windows-latest,  python: 3.8,  arch: x64 }
           - { os: windows-latest,  python: 3.7,  arch: x64 }
           - { os: windows-latest,  python: 3.6,  arch: x64 }
 
+          - { os: windows-latest,  python: 3.9,  arch: x86 }
           - { os: windows-latest,  python: 3.8,  arch: x86 }
           - { os: windows-latest,  python: 3.7,  arch: x86 }
           - { os: windows-latest,  python: 3.6,  arch: x86 }

setup.cfg

@@ -18,6 +18,7 @@ classifiers =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
 
 [options]
 zip_safe = False