ci: add Debian release build

Previously, we were running 'cargo deb' locally. But the release process
is a little simpler now thanks to GitHub Actions and the 'gh' tool, so I
felt comfortable putting the 'deb' generation in CI.

Now the only real manual part of release asset creation is the M2
release, but that should hopefully be automated once GitHub makes Apple
silicon runners available for free.

Cargo.toml

@@ -74,6 +74,13 @@ pcre2 = ["grep/pcre2"]
 [profile.release]
 debug = 1
 
+# This is the main way to strip binaries in the deb package created by
+# 'cargo deb'. For other release binaries, we (currently) call 'strip'
+# explicitly in the release process.
+[profile.deb]
+inherits = "release"
+debug = false
+
 [package.metadata.deb]
 features = ["pcre2"]
 section = "utils"