docs: Undo sphinx awkwardness with code blocks

This set "clear: both", which resulted in code blocks sometimes being
pushed down a lot, resulting in weird empty space.

Just undo it, I have no idea why it's there, presumably it makes sense
with sphinx' stock theme?

doc_src/python_docs_theme/static/pydoctheme.css

@@ -195,6 +195,11 @@ tt, code, pre {
     background-color: inherit;
 }
 
+pre, div[class*="highlight-"] {
+    /* For some reason sphinx since 3.1.2 sets "clear: both" here, which breaks in interesting ways */
+    clear: unset;
+}
+
 div.body tt, div.body code {
     border-radius: 3px;
 }