Fixed sphinx conf to detect PR builds and link to 'latest' instead of stable

Author: philipstarkey

docs/source/conf.py

@@ -133,8 +133,10 @@
 
 # whether to use stable or latest version
 labscript_suite_doc_version = os.environ.get('READTHEDOCS_VERSION', 'latest')
-if labscript_suite_doc_version not in ['stable', 'latest']:
+if '.' in labscript_suite_doc_version:
     labscript_suite_doc_version = 'stable'
+elif labscript_suite_doc_version not in ['stable', 'latest']:
+    labscript_suite_doc_version = 'latest'
 
 # add intersphinx references for each component
 for ls_prog in labscript_suite_programs: