fix: remove extra newlines in CONTRIBUTING.md

CONTRIBUTING_FINAL.md.liquid

@@ -13,6 +13,7 @@ There are some things that should be kept in mind when contributing to this proj
 * [`taplo`](https://github.com/tamasfe/taplo)
 * [`rust-analyzer`](https://github.com/rust-lang/rust-analyzer)
 {% if include_precommit -%}
+
 ### Using pre-commit hooks
 
 This project makes use of [`pre-commit`](https://pre-commit.com/) hooks. A `pre-commit install` is recommended once the repository has been cloned, unless it has been [auto-enabled](https://pre-commit.com/#automatically-enabling-pre-commit-on-repositories).
@@ -25,25 +26,21 @@ Pretty standard procedure apart from noting that some tests may be behind featur
 ```sh
 cargo test --all-features
 ```
-
 {% if include_mdbook -%}
 Book testing may be done by:
 
 ```sh
 mdbook test
 ```
 {%- endif %}
-
 ### Generating and opening documentation
 
 ```sh
 cargo doc --no-deps --all-features --open
 ```
-
 {% if include_mdbook -%}
 Book documentation may be generated by installing [`mdbook`](https://rust-lang.github.io/mdBook/guide/installation.html) before running `mdbook serve --open`.
 {%- endif %}
-
 ## Release (for maintainers)
 
 1. Make sure CI is not failing.