fix: Explicitly list each py37 environment for coverage exclusion

- List py37-ubuntu-22.04 and py37-macos-13 explicitly
- Place py37 settings before general windows-latest setting
- This should properly exclude aio module from coverage on Python 3.7

Author: taeold

tox.ini

@@ -33,9 +33,11 @@ extras =
     async
 setenv =
     PYTESTARGS = --cov=functions_framework --cov-branch --cov-report term-missing --cov-fail-under=100
-    windows-latest: PYTESTARGS =
     # Python 3.7: Exclude aio module from coverage since it requires Python 3.8+ (Starlette dependency)
-    py37-{ubuntu-22.04,macos-13,windows-latest}: PYTESTARGS = --cov=functions_framework --cov-branch --cov-report term-missing --cov-fail-under=100 --cov-omit='*/aio/*'
+    py37-ubuntu-22.04: PYTESTARGS = --cov=functions_framework --cov-branch --cov-report term-missing --cov-fail-under=100 --cov-omit='*/aio/*'
+    py37-macos-13: PYTESTARGS = --cov=functions_framework --cov-branch --cov-report term-missing --cov-fail-under=100 --cov-omit='*/aio/*'
+    py37-windows-latest: PYTESTARGS =
+    windows-latest: PYTESTARGS =
 commands = pytest {env:PYTESTARGS} {posargs}
 
 [testenv:lint]