Fix clippy issues

[jfrimmel]

Currently each PR has the following issue, which should be fixed:

Output of cargo clippy

    Checking cargo-valgrind v2.0.2 (/home/runner/work/cargo-valgrind/cargo-valgrind)
warning: consider adding a `;` to the last statement for consistent formatting
  --> src/panic.rs:76:13
   |
76 |             old_hook(panic)
   |             ^^^^^^^^^^^^^^^ help: add a `;` here: `old_hook(panic);`
   |
note: the lint level is defined here
  --> src/main.rs:9:5
   |
9  |     clippy::pedantic,
   |     ^^^^^^^^^^^^^^^^
   = note: `#[warn(clippy::semicolon_if_nothing_returned)]` implied by `#[warn(clippy::pedantic)]`
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

warning: this `impl` can be derived
   --> src/valgrind/xml/mod.rs:156:1
    |
156 | / impl Default for Resources {
157 | |     fn default() -> Self {
158 | |         Resources {
159 | |             bytes: 0,
...   |
162 | |     }
163 | | }
    | |_^
    |
note: the lint level is defined here
   --> src/main.rs:6:5
    |
6   |     clippy::complexity,
    |     ^^^^^^^^^^^^^^^^^^
    = note: `#[warn(clippy::derivable_impls)]` implied by `#[warn(clippy::complexity)]`
    = help: try annotating `valgrind::xml::Resources` with `#[derive(Default)]`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#derivable_impls

warning: unnecessary structure name repetition
   --> src/valgrind/xml/mod.rs:158:9
    |
158 |         Resources {
    |         ^^^^^^^^^ help: use the applicable keyword: `Self`
    |
note: the lint level is defined here
   --> src/main.rs:8:5
    |
8   |     clippy::nursery,
    |     ^^^^^^^^^^^^^^^
    = note: `#[warn(clippy::use_self)]` implied by `#[warn(clippy::nursery)]`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#use_self

warning: length comparison to zero
  --> src/valgrind/mod.rs:87:24
   |
87 |                     if new_err.len() > 0 {
   |                        ^^^^^^^^^^^^^^^^^ help: using `!is_empty` is clearer and more explicit: `!new_err.is_empty()`
   |
note: the lint level is defined here
  --> src/main.rs:7:5
   |
7  |     clippy::style,
   |     ^^^^^^^^^^^^^
   = note: `#[warn(clippy::len_zero)]` implied by `#[warn(clippy::style)]`
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#len_zero

warning: consider adding a `;` to the last statement for consistent formatting
  --> src/valgrind/mod.rs:88:25
   |
88 |                         output.errors = Some(new_err)
   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `output.errors = Some(new_err);`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

warning: consider adding a `;` to the last statement for consistent formatting
  --> src/valgrind/mod.rs:90:25
   |
90 |                         output.errors = None
   |                         ^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `output.errors = None;`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

warning: `cargo-valgrind` (bin "cargo-valgrind") generated 6 warnings
    Finished dev [unoptimized + debuginfo] target(s) in 1m 10s

If your PR introduced these issues, please try to address them.

Originally posted by @github-actions[bot] in #50 (comment)