Update heck requirement from 0.4 to 0.5

---
updated-dependencies:
- dependency-name: heck
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

dfhack-proto/Cargo.toml

@@ -20,7 +20,7 @@ protobuf-codegen = "3.4.0"
 protobuf = "3.4.0"
 dfhack-proto-srcs = { version = "0.8.0", path = "../dfhack-proto-srcs" }
 regex = "1"
-heck = "0.4"
+heck = "0.5"
 quote = "1.0.18"
 prettyplease = "0.2.4"
 syn = "2.0.15"