Upgrade docs to the sphinx 8

conf.py

@@ -37,6 +37,7 @@
     "redirects",
     "notfound.extension",
     "sphinx_copybutton",
+    "sphinxcontrib.googleanalytics"
 ]
 
 # Add any paths that contain templates here, relative to this directory.
@@ -55,6 +56,8 @@
 project = "PlatformIO"
 copyright = "2014-present, PlatformIO"
 
+googleanalytics_id = "G-LQZCKGZE94"
+
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
@@ -116,14 +119,10 @@
 # further.  For a list of options available for each theme, see the
 # documentation.
 html_theme_options = {
-    "analytics_id": "G-LQZCKGZE94",
     "logo_only": True,
     "display_version": False,
 }
 
-# Add any paths that contain custom themes here, relative to this directory.
-html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
 html_title = "%s %s documentation" % (