semver-compare: fix typings of semverCompare (#40300)

types/semver-compare/index.d.ts

@@ -1,8 +1,9 @@
 // Type definitions for semver-compare 1.0
 // Project: https://github.com/substack/semver-compare
 // Definitions by: Kovács Vince <https://github.com/vincekovacs>
+//                 Linus Unnebäck <https://github.com/LinusU>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
-declare function semverCompare<T>(a: T, b: T): number;
+declare function semverCompare(a: string, b: string): -1 | 0 | 1;
 
 export = semverCompare;