Bump default Xcode version to 12.4.
This doesn't affect Bazel due to
It has the risk of breaking downstream projects, but we'll have to fix or disable them then (remaining on an older Xcode version is not viable).
@@ -533,7 +533,7 @@ DEFAULT_PLATFORM = "ubuntu1804"
# release platform for all Linux downstream tests.
LINUX_BINARY_PLATFORM = "centos7"
-DEFAULT_XCODE_VERSION = "11.7"
+DEFAULT_XCODE_VERSION = "12.4"
XCODE_VERSION_REGEX = re.compile(r"^\d+\.\d+(\.\d+)?$")
XCODE_VERSION_OVERRIDES = {"10.2.1": "10.3", "11.2": "11.2.1", "11.3": "11.3.1"}
