refactor: remove unnecessary allow(clippy::indexing_slicing)

clippy::indexing_slicing is already allowed in test builds.

src/authres.rs

@@ -260,7 +260,6 @@ fn parse_authservid_candidates_config(config: &Option<String>) -> BTreeSet<&str>
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
     use tokio::fs;
     use tokio::io::AsyncReadExt;
 

src/configure.rs

@@ -611,8 +611,6 @@ pub enum Error {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::config::Config;
     use crate::login_param::EnteredServerLoginParam;

src/configure/auto_mozilla.rs

@@ -272,8 +272,6 @@ pub(crate) async fn moz_autoconfigure(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
 
     #[test]

src/configure/auto_outlook.rs

@@ -215,8 +215,6 @@ pub(crate) async fn outlk_autodiscover(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
 
     #[test]

src/location.rs

@@ -880,8 +880,6 @@ async fn maybe_send_locations(context: &Context) -> Result<Option<u64>> {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::config::Config;
     use crate::message::MessageState;

src/mimefactory.rs

@@ -2274,7 +2274,6 @@ mod tests {
         let msg = message.as_string();
 
         let header_end = msg.find("Hi").unwrap();
-        #[allow(clippy::indexing_slicing)]
         let headers = msg[0..header_end].trim();
 
         assert!(!headers.lines().any(|l| l.trim().is_empty()));

src/mimeparser.rs

@@ -2362,8 +2362,6 @@ async fn ndn_maybe_add_info_msg(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use mailparse::ParsedMail;
 
     use super::*;

src/provider.rs

@@ -288,8 +288,6 @@ pub fn get_provider_by_id(id: &str) -> Option<&'static Provider> {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::test_utils::TestContext;
 

src/test_utils.rs

@@ -1,7 +1,6 @@
 //! Utilities to help writing tests.
 //!
 //! This private module is only compiled for test runs.
-#![allow(clippy::indexing_slicing)]
 use std::collections::{BTreeMap, HashSet};
 use std::fmt::Write;
 use std::ops::{Deref, DerefMut};

src/tests/aeap.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::indexing_slicing)]
-
 use anyhow::Result;
 
 use crate::chat;

src/tools.rs

@@ -709,8 +709,6 @@ pub(crate) fn inc_and_check<T: PrimInt + AddAssign + std::fmt::Debug>(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use chrono::NaiveDate;
     use proptest::prelude::*;