ci: Replace requirements-testing.txt with a uv dependency group (#6693)

Author: alexander-alderman-webb

pyproject.toml

@@ -68,6 +68,11 @@ typing = [
     "botocore-stubs",
     "werkzeug",
 ]
+test = [
+    "dataclasses ; python_full_version < '3.7'",
+    "pytest>=6.0.0",
+    "pytest-cov",
+]
 
 #
 # Tool: Coverage

requirements-testing.txt

@@ -71,12 +71,8 @@ envlist =
 [testenv]
 ; SDK is installed via deps below to resolve all deps at once (tox-uv limitation)
 package = skip
+dependency_groups = test
 deps =
-    # if you change requirements-testing.txt and your change is not being reflected
-    # in what's installed by tox (when running tox locally), try running tox
-    # with the -r flag
-    -r requirements-testing.txt
-
     # === Common ===
     py3.8-common: hypothesis
     common: brotli