Patch cargo metadata for Fedora build

diff --git a/rust/hg-core/Cargo.toml b/rust/hg-core/Cargo.toml
--- a/rust/hg-core/Cargo.toml
+++ b/rust/hg-core/Cargo.toml
@@ -31,7 +31,7 @@ sha-1 = "0.10.0"
 twox-hash = "1.6.3"
 same-file = "1.0.6"
 tempfile = "3.3.0"
-toml = "0.6"
+toml = "0.8"
 thread_local = "1.1.4"
 crossbeam-channel = "0.5.6"
 log = "0.4.17"