add Python 3.9 to setup.cfg template (#698)

Author: alrex

Diff for: .github/workflows/test.yml

@@ -6,7 +6,7 @@ on:
     - 'release/*'
   pull_request:
 env:
-  CORE_REPO_SHA: d9c22a87b6bfc5ec332588c764f82c32f068b2c3
+  CORE_REPO_SHA: 10208c1be1e720925a80a66f711b8afbe67537f4
 
 jobs:
   build:

Diff for: _template/setup.cfg

@@ -37,6 +37,7 @@ classifiers =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
 
 [options]
 python_requires = >=3.6

Diff for: tox.ini

@@ -187,7 +187,7 @@ deps =
 setenv =
   ; override CORE_REPO_SHA via env variable when testing other branches/commits than main
   ; i.e: CORE_REPO_SHA=dde62cebffe519c35875af6d06fae053b3be65ec tox -e <env to test>
-  CORE_REPO_SHA={env:CORE_REPO_SHA:"main"}
+  CORE_REPO_SHA={env:CORE_REPO_SHA:main}
   CORE_REPO="git+https://github.com/open-telemetry/opentelemetry-python.git@{env:CORE_REPO_SHA}"
 
 changedir =