Support stable Python3.9. (#1748)

* Support stable Python3.9.

* Get back to 3.9-dev

* Add py39 to black usage.

* remove 3.9 temporarily.

.github/workflows/doc.yml

@@ -21,10 +21,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
 
       - name: Install dependencies
         run: |

.github/workflows/fuzz.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8] # Python3.9 should be added after fixing [https://github.com/Zac-HD/hypothesmith/issues/11].
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/primer.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
         os: [ubuntu-latest, windows-latest]
 
     steps:

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
         os: [ubuntu-latest, macOS-latest, windows-latest]
 
     steps:

CONTRIBUTING.md

@@ -19,7 +19,7 @@ unlikely to get accepted. You can still try but prepare to be disappointed.
 
 ## Technicalities
 
-Development on the latest version of Python is preferred. As of this writing it's 3.8.
+Development on the latest version of Python is preferred. As of this writing it's 3.9.
 You can use any operating system. I am using macOS myself and CentOS at work.
 
 Install all development dependencies using:

README.md

@@ -86,7 +86,7 @@ Options:
   -l, --line-length INTEGER       How many characters per line to allow.
                                   [default: 88]
 
-  -t, --target-version [py27|py33|py34|py35|py36|py37|py38]
+  -t, --target-version [py27|py33|py34|py35|py36|py37|py38|py39]
                                   Python versions that should be supported by
                                   Black's output. [default: per-file auto-
                                   detection]

docs/contributing_to_black.md

@@ -21,7 +21,7 @@ unlikely to get accepted. You can still try but prepare to be disappointed.
 
 ## Technicalities
 
-Development on the latest version of Python is preferred. As of this writing it's 3.8.
+Development on the latest version of Python is preferred. As of this writing it's 3.9.
 You can use any operating system. I am using macOS myself and CentOS at work.
 
 Install all development dependencies using:

docs/installation_and_usage.md

@@ -41,7 +41,7 @@ Options:
   -l, --line-length INTEGER       How many characters per line to allow.
                                   [default: 88]
 
-  -t, --target-version [py27|py33|py34|py35|py36|py37|py38]
+  -t, --target-version [py27|py33|py34|py35|py36|py37|py38|py39]
                                   Python versions that should be supported by
                                   Black's output. [default: per-file auto-
                                   detection]

readthedocs.yml

@@ -1,6 +1,6 @@
 version: 2
 python:
-  version: 3.8
+  version: 3.9
   install:
     - requirements: docs/requirements.txt
     - method: setuptools

setup.py

@@ -93,6 +93,7 @@ def get_long_description() -> str:
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3 :: Only",
         "Topic :: Software Development :: Libraries :: Python Modules",
         "Topic :: Software Development :: Quality Assurance",