ci: attach .deb and .rpm packages to releases and nightlies

Built by nfpm from the static musl binaries, with the man page and the
bash, zsh and fish completions. The names carry no version, so
releases/latest/download/soulseek-rs-amd64.deb stays a working link; the
nightly pair replaces itself on the rolling prerelease.

packaging/nfpm.yaml

@@ -0,0 +1,55 @@
+name: soulseek-rs
+arch: ${PKG_ARCH}
+platform: linux
+version: ${PKG_VERSION}
+version_schema: none
+release: "1"
+section: net
+priority: optional
+maintainer: Michel de Graaf <michel@re-invention.nl>
+description: |
+  Soulseek client for the terminal
+  A TUI, a scriptable command line and a daemon for the Soulseek
+  peer-to-peer network.
+vendor: Michel de Graaf
+homepage: https://re-invention.nl/soulseek-rs/
+license: MIT
+suggests:
+  - gnome-keyring
+contents:
+  - src: target/nfpm/soulseek-rs
+    dst: /usr/bin/soulseek-rs
+    file_info:
+      mode: 0755
+  - src: target/nfpm/soulseek-rs.1.gz
+    dst: /usr/share/man/man1/soulseek-rs.1.gz
+  - src: target/nfpm/soulseek-rs.bash
+    dst: /usr/share/bash-completion/completions/soulseek-rs
+  - src: target/nfpm/soulseek-rs.fish
+    dst: /usr/share/fish/vendor_completions.d/soulseek-rs.fish
+  - src: target/nfpm/_soulseek-rs
+    dst: /usr/share/zsh/vendor-completions/_soulseek-rs
+    packager: deb
+  - src: target/nfpm/_soulseek-rs
+    dst: /usr/share/zsh/site-functions/_soulseek-rs
+    packager: rpm
+  - dst: /usr/share/doc/soulseek-rs
+    type: dir
+    packager: rpm
+  - dst: /usr/share/licenses/soulseek-rs
+    type: dir
+    packager: rpm
+  - src: README.md
+    dst: /usr/share/doc/soulseek-rs/README.md
+    packager: deb
+  - src: README.md
+    dst: /usr/share/doc/soulseek-rs/README.md
+    packager: rpm
+    type: doc
+  - src: LICENSE
+    dst: /usr/share/doc/soulseek-rs/copyright
+    packager: deb
+  - src: LICENSE
+    dst: /usr/share/licenses/soulseek-rs/LICENSE
+    packager: rpm
+    type: license