Fix clippy lints

Author: killercup

src/assert.rs

@@ -341,6 +341,8 @@ impl OutputAssertionBuilder {
     ///     .stdout().not().contains("73")
     ///     .unwrap();
     /// ```
+    // No clippy, we don't want to implement std::ops::Not :)
+    #[cfg_attr(feature = "cargo-clippy", allow(should_implement_trait))]
     pub fn not(mut self) -> Self {
         self.expected_result = ! self.expected_result;
         self

src/output.rs

@@ -65,7 +65,7 @@ pub enum OutputKind {
 }
 
 impl OutputKind {
-    pub fn select<'a>(self, o: &'a Output) -> &'a [u8] {
+    pub fn select(self, o: &Output) -> &[u8] {
         match self {
             OutputKind::StdOut => &o.stdout,
             OutputKind::StdErr => &o.stderr,