fix: remove no_coverage feature

See:
- rust-lang/rust#84605
- rust-lang/rust#114656

Author: zitsen

taos-error/src/code/constants.rs

@@ -1,5 +1,4 @@
 /// Constant error string from both version 2.x and 3.x of libtaos
-#[cfg_attr(nightly, no_coverage)]
 pub const fn error_str_of(code: u32) -> Option<&'static str> {
     match code {
         0x0001 => Some("Action in progress"),

taos-error/src/lib.rs

@@ -1,5 +1,4 @@
 #![cfg_attr(nightly, feature(error_generic_member_access))]
-#![cfg_attr(nightly, feature(no_coverage))]
 use std::{
     any::Any,
     borrow::Cow,