Fix SyntaxWarning: invalid escape sequence

[cclauss]

This removes all those pesky warnings from our unittest output so now it looks like:
% coverage run -m unittest discover tests

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Ran 151 tests in 3.606s

% ruff check --select=W605 --fix # https://docs.astral.sh/ruff

Found 34 errors (34 fixed, 0 remaining).

% ruff rule W605

invalid-escape-sequence (W605)

Derived from the pycodestyle linter.

Fix is always available.

What it does

Checks for invalid escape sequences.

Why is this bad?

Invalid escape sequences are deprecated in Python 3.6.

Example

regex = "\.png$"

Use instead:

regex = r"\.png$"

Or, if the string already contains a valid escape sequence:

value = "new line\nand invalid escape \_ here"

Use instead:

value = "new line\nand invalid escape \\_ here"

References

• Python documentation: String and Bytes literals