misc: unify terminology

won't → unable to

Change-Id: I1ce5af3ac16ed364df62d20338507b714a47b913
GitLab: jami-client-qt#1730

src/upnp/protocol/natpmp/nat_pmp.cpp

@@ -441,7 +441,7 @@ NatPmp::sendMappingRequest(Mapping& mapping, uint32_t& lifetime)
         // Unfortunately, libnatpmp only allows reading one response per request sent; calling
         // readResponse again at this point would result in a NATPMP_ERR_NOPENDINGREQ error.
         // Since it is unable to known whether the mapping was actually created or not, we return an
-        // error to ensure the caller won't attempt to use a port mapping that doesn't exist.
+        // error to ensure the caller is unable to attempt to use a port mapping that doesn't exist.
         return NATPMP_ERR_INVALIDARGS;
     }