`locust` forces upper bound on `gevent` version

[achave11-ucsc]

… which causes the make requirements_update target to fail if the gevent requirement is updated to a version > 25.0.0.

ERROR: Cannot install -r requirements.dev.txt (line 16) and gevent==25.5.1 because these package versions have conflicting dependencies.

The conflict is caused by:
    The user requested gevent==25.5.1
    locust 2.37.3 depends on gevent<25.0.0 and >=24.10.1

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip to attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/topics/dependency-resolution/#dealing-with-dependency-conflicts
make: *** [Makefile:33: requirements_deps] Error 1

[achave11-ucsc]

@hannes-ucsc: "Assignee to remove our dependency on locust (move scripts to attic, remove related documentation and eliminate entry in requirements.dev.txt)."