Valgrind 5 (rekey tests) are taking far too long and

leading to multiple other CI test being cancelled as
the time limit is exceeded. We'll return to this one
as soon as we figure out a few things.

Author: rapier1

.github/workflows/c-cpp.yml

@@ -28,7 +28,7 @@ jobs:
           - { target: ubuntu-20.04, config: valgrind-2 }
           - { target: ubuntu-20.04, config: valgrind-3 }
           - { target: ubuntu-20.04, config: valgrind-4 }
-          - { target: ubuntu-20.04, config: valgrind-5 }
+#          - { target: ubuntu-20.04, config: valgrind-5 }
           - { target: ubuntu-20.04, config: valgrind-6 }
           - { target: ubuntu-20.04, config: valgrind-7 }
           - { target: ubuntu-20.04, config: c89 }