Escaping in the docs is required

[ratijas]

When executing %load_ext sql in a Jupyter Notebook, it raises two warnings:

/opt/python3.13/site-packages/sql/parse.py:339: SyntaxWarning: invalid escape sequence '\:'
  Given a query, replaces all occurrences of ':variable' with '\:variable' and
  /opt/python3.13/site-packages/sql/parse.py:369: SyntaxWarning: invalid escape sequence '\:'
  Given a query, replaces all occurrences of 'example'[x:y] with 'example'[x\:y].

• https://github.com/ploomber/jupysql/blame/6f83dbec7659124efe00c8ab1c3838b404fc0f3f/src/sql/parse.py#L337-L344
• https://github.com/ploomber/jupysql/blame/6f83dbec7659124efe00c8ab1c3838b404fc0f3f/src/sql/parse.py#L367-L371