Merge pull request diffblue#7664 from NlightNFotis/remove_cargo_lock

Remove `Cargo.lock` as recommended by Rust docs.

Author: NlightNFotis

src/libcprover-rust/.gitignore

@@ -1,2 +1,5 @@
 # Ignore build artefacts folder
 target/
+
+# Ignore Cargo.lock as recommended by Rust docs
+Cargo.lock

src/libcprover-rust/Cargo.lock

@@ -6,7 +6,7 @@ description = "Rust API for CBMC and assorted CProver tools"
 repository = "https://github.com/diffblue/cbmc"
 documentation = "https://diffblue.github.io/cbmc/"
 license = "BSD-4-Clause"
-exclude = ["module_dependencies.txt"]
+exclude = ["module_dependencies.txt", "Cargo.lock"]
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html