Ensure consistent spoilage estimate in test

item.cpp#L934 `get_freshness_description` gives more detailed rot
estimation messages to more skilled characters. Travis-CI revealed this
test failing sometimes; this commit should ensure a consistent (0) skill
level when testing these messages.

tests/iteminfo_test.cpp

@@ -184,6 +184,10 @@ TEST_CASE( "food freshness and lifetime", "[item][iteminfo]" )
 {
     iteminfo_query q( { iteminfo_parts::FOOD_ROT } );
 
+    // Ensure test character has no skill estimating spoilage
+    g->u.empty_skills();
+    REQUIRE_FALSE( g->u.can_estimate_rot() );
+
     SECTION( "food is fresh" ) {
         iteminfo_test(
             item( "pine_nuts" ), q,