Bump a2wsgi from 1.7.0 to 1.8.0 (#2142)

Bumps [a2wsgi](https://github.com/abersheeran/a2wsgi) from 1.7.0 to 1.8.0.
- [Commits](abersheeran/a2wsgi@v1.7.0...v1.8.0)

---
updated-dependencies:
- dependency-name: a2wsgi
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -5,7 +5,7 @@
 h11 @ git+https://github.com/python-hyper/h11.git@master
 
 # Explicit optionals
-a2wsgi==1.7.0
+a2wsgi==1.8.0
 wsproto==1.2.0
 websockets==11.0.3