trivial syntax fix to avoid SyntaxWarning

[mperrin]

Trivial (one character!) fix to avoid a SyntaxWarning in python 3.12+. Starting in 3.12, python has gotten stricter about backslash escape sequences in strings.

Without this fix:

In [1]: import pysiaf
pysiaf/pysiaf/aperture.py:1401: SyntaxWarning: invalid escape sequence '\*'
  """Sky to Tel frame transformation. Requires an attitude matrix.

With this fix: No warning is produced. .

[Witchblade101]

@mfixstsci Let's merge this and add back the 3.12 support temporarily removed from the CI the other day.

[mfixstsci]

Sounds good @Witchblade101