remove extra whitespace when running cargo -Z help

Author: gdoenlen

src/bin/cargo/cli.rs

@@ -43,7 +43,7 @@ Available unstable (nightly-only) flags:
     -Z doctest-xcompile    -- Compile and run doctests for non-host target using runner config
     -Z terminal-width      -- Provide a terminal width to rustc for error truncation
     -Z namespaced-features -- Allow features with `dep:` prefix
-    -Z weak-dep-features    -- Allow `dep_name?/feature` feature syntax
+    -Z weak-dep-features   -- Allow `dep_name?/feature` feature syntax
 
 Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
         );