tests/pkg_edhoc_c: blacklist esp32-wroom-32

This test fails rather regularly on CI, so disable it.

socat - open:/dev/ttyUSB0,b115200,echo=0,raw
Traceback (most recent call last):
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/tests/pkg_edhoc_c/tests/01-run.py", line 101, in <module>
    sys.exit(run(testfunc))
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/dist/pythonlibs/testrunner/__init__.py", line 28, in run
    logfile=sys.stdout if echo else None)
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/dist/pythonlibs/testrunner/spawn.py", line 88, in setup_child
    sync_child(child, env)
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/dist/pythonlibs/testrunner/spawn.py", line 123, in sync_child
    TEST_INTERACTIVE_DELAY)
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/dist/pythonlibs/testrunner/utils.py", line 41, in test_utils_interactive_sync_shell
    _test_utils_interactive_sync(child, retries, delay, '\n', '>')
  File "/tmp/dwq.0.5480675865160537/2c1d3acc7a86753de0db3a13fc04973d/dist/pythonlibs/testrunner/utils.py", line 17, in _test_utils_interactive_sync
    ret = child.expect_exact([ready_exp, pexpect.TIMEOUT], timeout=delay)
  File "/usr/local/lib/python3.5/dist-packages/pexpect/spawnbase.py", line 421, in expect_exact
    return exp.expect_loop(timeout)
  File "/usr/local/lib/python3.5/dist-packages/pexpect/expect.py", line 179, in expect_loop
    return self.eof(e)
  File "/usr/local/lib/python3.5/dist-packages/pexpect/expect.py", line 122, in eof
    raise exc
pexpect.exceptions.EOF: End Of File (EOF). Exception style platform.

tests/pkg_edhoc_c/Makefile

@@ -6,6 +6,9 @@ BOARD_WHITELIST += $(BOARD_PROVIDES_NETIF)
 #   open(/dev/net/tun): No such file or directory
 TEST_ON_CI_BLACKLIST += native
 
+# Test fails pretty regularly on CI
+TEST_ON_CI_BLACKLIST += esp32-wroom-32
+
 # Edhoc related packages
 USEPKG += edhoc-c
 USEMODULE += edhoc-c_crypto_tinycrypt