Remove const_panic feature

Thomasdezeeuw · Thomasdezeeuw · commit af3286a879f4 · 2021-10-09T12:05:54.000+02:00
It's been stabilized in rust-lang/rust#89508.
diff --git a/http/src/lib.rs b/http/src/lib.rs
@@ -4,7 +4,6 @@
     async_stream,
     const_fn_trait_bound,
     const_mut_refs,
-    const_panic,
     drain_filter,
     generic_associated_types,
     io_slice_advance,
