chore(deps): bump tox from 3.25.1 to 3.28.0 in /requirements

Bumps [tox](https://github.com/tox-dev/tox) from 3.25.1 to 3.28.0.
- [Release notes](https://github.com/tox-dev/tox/releases)
- [Changelog](https://github.com/tox-dev/tox/blob/3.28.0/docs/changelog.rst)
- [Commits](tox-dev/tox@3.25.1...3.28.0)

---
updated-dependencies:
- dependency-name: tox
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements/integration.txt

@@ -32,15 +32,15 @@ packaging==21.3
 pep517==0.11.0
     # via build
 pip-compile-multi==2.4.1
-    # via -r requirements/integration.in
+    # via -r integration.in
 pip-tools==6.8.0
     # via pip-compile-multi
 platformdirs==2.2.0
     # via virtualenv
 pluggy==0.13.1
     # via tox
 pre-commit==2.14.0
-    # via -r requirements/integration.in
+    # via -r integration.in
 py==1.10.0
     # via tox
 pyparsing==3.0.6
@@ -52,15 +52,13 @@ six==1.16.0
     #   tox
     #   virtualenv
 toml==0.10.2
-    # via
-    #   pre-commit
-    #   tox
+    # via pre-commit
 tomli==1.2.1
-    # via build
+    # via pep517
 toposort==1.6
     # via pip-compile-multi
-tox==3.25.1
-    # via -r requirements/integration.in
+tox==3.28.0
+    # via -r integration.in
 virtualenv==20.7.2
     # via
     #   pre-commit