Fix the edition core-no-fp-fmt-parse is using

The `Cargo.toml` has `edition = "2021"`, so that's what the command line should use too.

Author: scottmcm

src/test/run-make-fulldeps/core-no-fp-fmt-parse/Makefile

@@ -1,4 +1,4 @@
 -include ../tools.mk
 
 all:
-	$(RUSTC) --edition=2018 --crate-type=rlib ../../../../library/core/src/lib.rs --cfg no_fp_fmt_parse
+	$(RUSTC) --edition=2021 --crate-type=rlib ../../../../library/core/src/lib.rs --cfg no_fp_fmt_parse