Commit the Cargo.lock file to build with known working versions of dependencies

This offloads _some_ care to consumers, as by default they might now
pull in transitive dependencies that break UniFFI's MSRV.
What they will need to do is `cargo update -p $dep --precise $ver`
where `$ver` is a version that is MSRV-compatible (and is probably the
one uniffi's Cargo.lock file contains)

Author: badboy

.gitignore

@@ -1,4 +1,3 @@
-Cargo.lock
 target
 .*.swp
 *.jar