0.31.0: build against libfreemkv 0.31; add self-contained leak-guard CI; thin LTO release profile

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "freemkv-keysources"
-version = "0.30.0"
+version = "0.31.0"
 edition = "2024"
 license = "AGPL-3.0-only"
 description = "Pluggable AACS key sources (keydb, online key service, mapfile) for libfreemkv. Each source looks a disc up and hands libfreemkv a Key; the library does all derivation."
@@ -10,8 +10,12 @@ categories = ["multimedia"]
 
 [dependencies]
 # The crate provides the `KeySource` trait + `Key`/`DiscInputs` types these impls fill.
-libfreemkv = "0.30"
+libfreemkv = "0.31"
 # OnlineSource: POST disc inputs + samples to a key service over HTTP.
 ureq = { version = "2", features = ["json"] }
 serde_json = "1"
 base64 = "0.22"
+
+[profile.release]
+lto = "thin"
+codegen-units = 1