Fix linter warnings

Cargo.toml

@@ -1,5 +1,3 @@
-cargo-features = ["edition2021"]
-
 [package]
 name = "mensa"
 version = "0.5.0"

src/cache/fetchable.rs

@@ -2,7 +2,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::error::Result;
 
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(from = "T", untagged)]
 pub enum Fetchable<T> {
     /// The value does not exist, but can be fetched.

src/main.rs

@@ -1,4 +1,3 @@
-#![feature(macro_attributes_in_derive_output)]
 //! <img src="https://raw.githubusercontent.com/MalteT/mensa/main/static/logo.png" alt="mensa CLI logo" width="400" align="right">
 //!
 //! [![tests](https://github.com/MalteT/mensa/actions/workflows/rust.yml/badge.svg)](https://github.com/MalteT/mensa/actions/workflows/rust.yml)

src/request/mod.rs

@@ -14,7 +14,7 @@ mod dummy;
 pub use self::dummy::DummyApi as DefaultApi;
 
 /// Assortment of headers relevant to the program.
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[non_exhaustive]
 pub struct Headers {
     pub etag: Option<String>,

src/request/reqwest.rs

@@ -55,33 +55,29 @@ impl From<reqwest::header::HeaderMap> for Headers {
         use reqwest::header::*;
         let etag = map
             .get(ETAG)
-            .map(|raw| {
+            .and_then(|raw| {
                 let utf8 = raw.to_str().ok()?;
                 Some(utf8.to_string())
-            })
-            .flatten();
+            });
         let this_page = map
             .get("x-current-page")
-            .map(|raw| {
+            .and_then(|raw| {
                 let utf8 = raw.to_str().ok()?;
                 utf8.parse().ok()
-            })
-            .flatten();
+            });
         let next_page = map
             .get(LINK)
-            .map(|raw| {
+            .and_then(|raw| {
                 let utf8 = raw.to_str().ok()?;
                 let captures = LINK_NEXT_PAGE_RE.captures(utf8)?;
                 Some(captures[1].to_owned())
-            })
-            .flatten();
+            });
         let last_page = map
             .get("x-total-pages")
-            .map(|raw| {
+            .and_then(|raw| {
                 let utf8 = raw.to_str().ok()?;
                 utf8.parse().ok()
-            })
-            .flatten();
+            });
         Self {
             etag,
             this_page,