riemann: 0.2.12 -> 0.3.0

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0/bin/.riemann-wrapped -h` got 0 exit code
- ran `/nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0/bin/.riemann-wrapped -h` and found version 0.3.0
- ran `/nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0/bin/riemann -h` got 0 exit code
- ran `/nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0/bin/riemann -v` and found version 0.3.0
- ran `/nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0/bin/riemann -h` and found version 0.3.0
- found 0.3.0 with grep in /nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0
- found 0.3.0 in filename of file in /nix/store/5pk3bc05rja1qsq11zlp7x4pz8j2wcin-riemann-0.3.0

cc "@rickynils"