Switch to using the v2 resolver in library/

Pinning the resolver to v1 was done in 5abff37 ("Explicit set
workspace.resolver ...") in order to suppress warnings. Since there is
no specific reason not to use the new resolver and since it fixes
issues, change to `resolver = "2"` in `library/`.

Author: tgross35

library/Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-resolver = "1"
+resolver = "2"
 members = [
   "std",
   "sysroot",