Fix the script bug in importing-a-subversion-repository.md

Fix the bug in the author extraction script that causes author's starting from 't' losing it, e.g.

SVN log:
```
r5572 | toe | 2023-04-10 09:25:13 -0400 (Mon, 10 Apr 2023)
``
Result mapping:
```
om  =  tom
```

The corrected script produces the expected mapping:
```
tom  =  tom
```

Author: nih-dk

content/migrations/importing-source-code/using-the-command-line-to-import-source-code/importing-a-subversion-repository.md

@@ -33,7 +33,7 @@ To follow these steps, you must use a macOS or Linux system and have the followi
 1. To get a list of authors in your Subversion project and store the list in `authors.txt`, run the following script:
 
    ```shell copy
-   svn log -q | grep -e '^r' | awk 'BEGIN { FS = "|" } ; { print $2" = "$2 }' | sed 's/^[ \t]*//' | sort | uniq > authors.txt
+   svn log -q | grep -e '^r' | awk 'BEGIN { FS = "|" } ; { print $2" = "$2 }' | sed -E 's/^ *//' | sort | uniq > authors.txt
    ```
 
 1. Update your `authors.txt` file, mapping the author name used in the Subversion repository to the name you want to use in your Git repository, with the following format: