Fix missing locked arg in cargo install (#10374)

Signed-off-by: Vasyl Gello <vasek.gello@gmail.com>

flutter/build_fdroid.sh

@@ -237,7 +237,9 @@ prebuild)
 
 	# Install rust bridge generator
 
-	cargo install cargo-expand
+	cargo install \
+		cargo-expand \
+		--locked
 	cargo install flutter_rust_bridge_codegen \
 		--version "${FLUTTER_RUST_BRIDGE_VERSION}" \
 		--features "uuid" \