[pre-commit.ci] auto fixes from pre-commit.com hooks

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Author: pre-commit-ci[bot]

TESTING.md

@@ -3,7 +3,7 @@
 ``ARTIST`` uses ``pytest`` for running the test suite.
 
 To run the tests make sure you have the project and all dependencies installed.
-Refer to the [Installation](https://github.com/ARTIST-Association/ARTIST/blob/main/README.md#installation) instructions on how to install artist and make sure to choose the option of installing an editable version with developer dependencies: 
+Refer to the [Installation](https://github.com/ARTIST-Association/ARTIST/blob/main/README.md#installation) instructions on how to install artist and make sure to choose the option of installing an editable version with developer dependencies:
 ```bash
 pip install -e ."[dev]"
 ```