Switch to new Furo docs theme (Qiskit/qiskit-metapackage#1784)

See Qiskit#10498 for the
motivation.

Note that in Terra, we distinguish between dev/CI builds vs. prod
builds. We don't make that distinguishment here because we don't get
much dev activity in this repo.

docs/conf.py

@@ -149,19 +149,7 @@
 
 # -- Options for HTML output -------------------------------------------------
 
-html_theme = "qiskit_sphinx_theme"
-html_theme_options = {
-    "logo_only": False,
-    "display_version": True,
-    "prev_next_buttons_location": "bottom",
-    "style_external_links": True,
-    # Toc options
-    "collapse_navigation": True,
-    "sticky_navigation": True,
-    "navigation_depth": 4,
-    "includehidden": True,
-    "titles_only": False,
-}
+html_theme = "qiskit"
 html_favicon = "images/favicon.ico"
 html_last_updated_fmt = "%Y/%m/%d"
 html_context = {