Fix New Clippy Lints

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Latest clippy produces warnings like

warning: this lifetime isn't used in the impl
   --> parquet/src/encodings/decoding.rs:842:6
    |
842 | impl<'m, T: DataType> Decoder<T> for DeltaByteArrayDecoder<T> {

warning: `format!(..)` appended to existing `String`
   --> arrow/src/util/display.rs:211:17
    |
211 |                 tmp += &format!("{:02x}", character);

Describe the solution you'd like
We should fix this

[tustvold]

Duplicate #1984