ci: Pin redis<8 for rq (#6438)

Author: sl0thentr0py

scripts/populate_tox/config.py

@@ -383,7 +383,7 @@
         "deps": {
             # https://github.com/jamesls/fakeredis/issues/245
             # https://github.com/cunla/fakeredis-py/issues/341
-            "*": ["fakeredis<2.28.0"],
+            "*": ["fakeredis<2.28.0", "redis<8.0.0"],
             "<0.9": ["fakeredis<1.0", "redis<3.2.2"],
             ">=0.9,<0.14": ["fakeredis>=1.0,<1.7.4"],
             "py3.6,py3.7": ["fakeredis!=2.26.0"],