Just ... don't install it special

We should get it from setup.cfg dependencies later

.github/workflows/ci.yaml

@@ -43,10 +43,6 @@ jobs:
       run: |
         python -m pip install wheel coverage
 
-    - name: "Install python-challenge-bypass-ristretto master@HEAD"
-      run: |
-        python -m pip install git+https://github.com/LeastAuthority/python-challenge-bypass-ristretto@master#egg=python-challenge-bypass-ristretto
-
     - name: "Install Tahoe-LAFS master@HEAD"
       run: |
         python -m pip install git+https://github.com/tahoe-lafs/tahoe-lafs@master#egg=tahoe-lafs