Remove deprecated get_html_theme_path (#352)

The goal is for the 1.13 theme release to include Furo, so this function
doesn't make sense.

qiskit_sphinx_theme/__init__.py

@@ -13,7 +13,6 @@
 """Pytorch Sphinx theme."""
 
 from pathlib import Path
-from warnings import warn
 
 from qiskit_sphinx_theme import directives, previous_releases, translations
 
@@ -26,24 +25,6 @@ def _get_theme_absolute_path(folder_name: str) -> str:
     return str(path.resolve())
 
 
-def get_html_theme_path():
-    """Return the absolute path to this package.
-
-    This is traditionally used to set the option `html_theme_path`, but that should not be
-    necessary. If you install the `qiskit_sphinx_theme` via pip, you only need to set `html_theme`.
-    """
-    warn(
-        "`qiskit_sphinx_theme.get_html_theme_path()` is deprecated and will be removed in version "
-        "1.13 of the package. We are adding multiple 'variants' / theme names to the package, so "
-        "the function no longer makes semantic sense.\n\n"
-        "It should not be necessary to set the option `html_theme_path`; you only need to set "
-        "`html_theme`. See https://github.com/Qiskit/qiskit-finance/pull/244 for an example.",
-        stacklevel=2,
-        category=DeprecationWarning,
-    )
-    return _get_theme_absolute_path("pytorch_base")
-
-
 # See https://www.sphinx-doc.org/en/master/development/theming.html
 def setup(app):
     # Used to generate URL references. Expected to be e.g. `ecosystem/finance`.