worker: 3.8.5 -> 3.15.0

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker -h` got 0 exit code
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker --help` got 0 exit code
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker help` got 0 exit code
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker -V` and found version 3.15.0
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker -v` and found version 3.15.0
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker --version` and found version 3.15.0
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker -h` and found version 3.15.0
- ran `/nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0/bin/worker --help` and found version 3.15.0
- found 3.15.0 with grep in /nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0
- found 3.15.0 in filename of file in /nix/store/r4nbmymh7w5xqig9szbc6rmw2ld2gc91-worker-3.15.0

cc "@ndowens"