Fix typo

Co-authored-by: Teymour Aldridge <42674621+teymour-aldridge@users.noreply.github.com>

tests/testsuite/jobserver.rs

@@ -52,7 +52,7 @@ fn jobserver_exists() {
         .build();
 
     // Explicitly use `-j2` to ensure that there's eventually going to be a
-    // token to read from `valdiate` above, since running the build script
+    // token to read from `validate` above, since running the build script
     // itself consumes a token.
     p.cargo("build -j2").run();
 }