Rust: fix toolchain version for tests

Author: Paolo Tranquilli

rust/rust-toolchain.toml

@@ -0,0 +1,8 @@
+# This file specifies the Rust version used to develop and test the rust
+# extractor. It is set to the lowest version of Rust we want to support.
+# IMPORTANT: this can also have an impact on QL test results
+
+[toolchain]
+channel = "1.84"
+profile = "minimal"
+components = [ "clippy", "rustfmt" ]