Update invalid EC key test for compatibility with upcoming OpenSSL ch…

…anges

One of the tests checking behavior with invalid EC keys hardcoded the
error reason.

This commit replaces the string matching with a regex to match both the
current string and a new reason, introduced by upcoming OpenSSL
changes [0], which would otherwise trigger a false positive failure.

[0]: openssl/openssl#19681

tests/hazmat/primitives/test_ec.py

@@ -411,7 +411,9 @@ def test_load_invalid_ec_key_from_pem(self, backend):
         # BoringSSL rejects infinity points before it ever gets to us, so it
         # uses a more generic error message.
         match = (
-            "infinity" if not backend._lib.CRYPTOGRAPHY_IS_BORINGSSL else None
+            r"infinity|invalid form"
+            if not backend._lib.CRYPTOGRAPHY_IS_BORINGSSL
+            else None
         )
         with pytest.raises(ValueError, match=match):
             serialization.load_pem_public_key(