fix(bip85): gate tests on 7.15.0, not 7.14.0 — BIP-85 landed in 7.15

test_msg_bip85 gated requires_firmware("7.14.0"), but GetBip85Mnemonic
was introduced in 7.15.0. On 7.14.x firmware the version gate passed and
the real GetBip85Mnemonic call hit Failure_UnexpectedMessage ("Unknown
message"), turning the suite red (6 failures) instead of skipping. Bump
the floor to 7.15.0 so firmware without BIP-85 skips cleanly and CI stays
green regardless of which firmware the emulator is built from. The
redundant requires_message("GetBip85Mnemonic") probe is dropped — it
no-ops on required-field messages, and the version gate now covers it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: BitHighlander

tests/test_msg_bip85.py

@@ -1,6 +1,6 @@
 """BIP-85 display-only tests.
 
-Firmware >= 7.14.0 derives the BIP-85 child mnemonic, displays it on the
+Firmware >= 7.15.0 derives the BIP-85 child mnemonic, displays it on the
 device screen, and responds with Success (mnemonic is never sent over USB).
 
 Tests verify:
@@ -19,8 +19,7 @@ class TestMsgBip85(common.KeepKeyTest):
 
     def setUp(self):
         super().setUp()
-        self.requires_firmware("7.14.0")
-        self.requires_message("GetBip85Mnemonic")
+        self.requires_firmware("7.15.0")
 
     def test_bip85_12word_flow(self):
         """12-word derivation: verify device goes through display flow and returns Success."""