test: disable test/app/digest.test.lua on macOS/M1

After we moved osx testing from the per-commit to nightly basis [1],
we accidentally enabled running tarantool tests on macOS/M1 for 2.10.
So we had some tests failed, and they were fixed by cherry-picking a
few commits from the master branch [2]. Also, some tests were fixed by
updating test-run to the new version [3] with needed fix [4]. So it's
time to fix the last failed test (test/app/digest.test.lua) on macOS/M1
by disabling it due to the issue [5].

[1] #9571
[2] #9672
[3] #9685
[4] tarantool/test-run#422
[5] #6097

NO_DOC=testing stuff
NO_TEST=testing stuff
NO_CHANGELOG=testing stuff

test/app/digest.skipcond

@@ -3,5 +3,11 @@ import platform
 # Disabled on OpenBSD due to fail #XXXX.
 if platform.system() == 'OpenBSD':
     self.skip = 1
+# Disabled on macOS/M1 due to issue #6097.
+elif platform.system() == 'Darwin' and platform.machine() == 'arm64'
+    self.skip = 1
+# Enabled on others.
+else
+    self.skip = 0
 
 # vim: set ft=python: