[Fr] Add "pour cent" in the expansion rule <pourcent>

this PR is related to home-assistant#2064

In Fench, Whisper is sometimes returning "pourcent" in two words.
--> "pour cent" added in the related expansion rule

sentences/fr/_common.yaml

@@ -511,7 +511,7 @@ lists:
 
 expansion_rules:
   #Common rules
-  pourcent: "(%| %| pourcent)"
+  pourcent: "(%| %| pourcent| pour cent)"
   degres: "(°| °| degré| degrés)"
   le: (le |la |les |l')
   dans: "(dans|du|de|des|à|au|aux|sur)"