Add a floating-point suffix to silence warnings; NFC

This silences about 6000 warnings about truncating from double to float
with Visual Studio.

Author: AaronBallman

clang-tools-extra/clangd/quality/CompletionModelCodegen.py

@@ -40,7 +40,7 @@ def header_guard(filename):
 
 def boost_node(n, label, next_label):
     """Returns code snippet for a leaf/boost node."""
-    return "%s: return %s;" % (label, n['score'])
+    return "%s: return %sf;" % (label, n['score'])
 
 
 def if_greater_node(n, label, next_label):