Silence some Clippy lints

These don't make the code any better.

Author: Thomasdezeeuw

src/kv/key.rs

@@ -41,6 +41,7 @@ pub struct Key<'k> {
 
 impl<'k> Key<'k> {
     /// Get a key from a borrowed string.
+    #[allow(clippy::should_implement_trait)] // Part of the public API now.
     pub fn from_str(key: &'k str) -> Self {
         Key { key }
     }

src/kv/source.rs

@@ -237,6 +237,7 @@ pub trait VisitSource<'kvs> {
     fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error>;
 }
 
+#[allow(clippy::needless_lifetimes)] // Not needless.
 impl<'a, 'kvs, T> VisitSource<'kvs> for &'a mut T
 where
     T: VisitSource<'kvs> + ?Sized,

src/kv/value.rs

@@ -535,6 +535,7 @@ pub trait VisitValue<'v> {
     }
 }
 
+#[allow(clippy::needless_lifetimes)] // Not needless.
 impl<'a, 'v, T: ?Sized> VisitValue<'v> for &'a mut T
 where
     T: VisitValue<'v>,