Remove redudant pip install commands for workflow. (#145)

* Remove redudant pip install commands for workflow.

Surfaced by Chenyu in review of dbt-redshift PR 105. These are already found in the dev_requirements.txt and don't need explicit inclusion like so

* Add changelog.

Co-authored-by: Mila Page <versusfacit@users.noreply.github.com>

.github/workflows/main.yml

@@ -53,8 +53,6 @@ jobs:
       - name: Install python dependencies
         run: |
           pip install --user --upgrade pip
-          pip install pre-commit
-          pip install mypy==0.782
           pip install -r dev_requirements.txt
           pip --version
           pre-commit --version

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Under the hood
 - Add precommits for this repo ([#107](https://github.com/dbt-labs/dbt-snowflake/pull/107))
+- Cleanup redundant precommit hook command ([#145](https://github.com/dbt-labs/dbt-snowflake/pull/145))
 
 ## dbt-snowflake 1.1.0b1 (March 23, 2022)