[3.13] gh-145642: Docs: Avoid warning for invalid escape sequence in tutorial (GH-145643) (#145646)

gh-145642: Docs: Avoid warning for invalid escape sequence in tutorial (GH-145643)

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(cherry picked from commit 5a15a52dd1dee37af4f2b3a6b15a9f5735f75c6e)

Co-authored-by: James <snoopjedi@gmail.com>
Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>