feat(core): plural function supports "key/keys" string

Previously function did not work for words ending with "y" and vowel before that

core/src/trezor/strings.py

@@ -39,7 +39,8 @@ def format_plural(string: str, count: int, plural: str) -> str:
         raise ValueError
 
     if count == 0 or count > 1:
-        if plural[-1] == "y":
+        # candy -> candies, but key -> keys
+        if plural[-1] == "y" and plural[-2] not in "aeiouy":
             plural = plural[:-1] + "ies"
         elif plural[-1] in "hsxz":
             plural = plural + "es"

core/tests/test_trezor.strings.py

@@ -17,10 +17,12 @@ class TestStrings(unittest.TestCase):
 
     def test_format_plural(self):
         VECTORS = [
-            ("We need {count} more {plural}", 3, "share", "We need 3 more shares"),
             ("We need {count} more {plural}", 1, "share", "We need 1 more share"),
+            ("We need {count} more {plural}", 3, "share", "We need 3 more shares"),
             ("We need {count} more {plural}", 1, "candy", "We need 1 more candy"),
             ("We need {count} more {plural}", 7, "candy", "We need 7 more candies"),
+            ("We need {count} more {plural}", 1, "key", "We need 1 more key"),
+            ("We need {count} more {plural}", 5, "key", "We need 5 more keys"),
             ("We need {count} more {plural}", 1, "hash", "We need 1 more hash"),
             ("We need {count} more {plural}", 2, "hash", "We need 2 more hashes"),
             ("We need {count} more {plural}", 1, "fuzz", "We need 1 more fuzz"),