Disabled failing test envs on py27/macos/min and pypy3

Details:

* The tests on Python 2.7 on macOS with minimum package levels fail in
  'make sanity' with what appears to be an internal error in Ansible 2.9.
  It only happens with minimum package levels, and it only happens on macOS.
  Trying higher Ansible 2.9 patch versions up to 2.9.15 did not solve the
  issue.
  Link to the Travis run showing the failure:
  https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432871
  Mitigation for now is to disable this test environment.

* The tests on Pypy3 (Python 3.6) fail when installing the 'cryptography'
  package because cryptography complains about the use of OpenSSL 1.0.2 in
  this environment. This happens with both the minimum version of cryptography
  (3.0) and the latest version (3.2.1).
  Links to the Travis runs showing the failure:
  https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432869
  https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432870
  Mitigation for now is to disable this test environment.

Signed-off-by: Andreas Maier <maiera@de.ibm.com>

.travis.yml

@@ -98,18 +98,27 @@ jobs:
 #      env:
 #        - PACKAGE_LEVEL=latest
 
+# Disabled for now.
+# This fails because cryptography complains about usage of OpenSSL 1.0.2;
+# see https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432869
 #    - os: linux
 #      language: python
 #      python: "pypy3"  # currently Python 3.6.1, PyPy 7.1.1-beta0
 #      env:
 #        - PACKAGE_LEVEL=minimum
 
+# Disabled for now.
+# This fails because cryptography complains about usage of OpenSSL 1.0.2;
+# see https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432870
 #    - os: linux
 #      language: python
 #      python: "pypy3"  # currently Python 3.6.1, PyPy 7.1.1-beta0
 #      env:
 #        - PACKAGE_LEVEL=latest
 
+# Disabled for now.
+# This fails in the Ansible sanity test;
+# see https://travis-ci.com/github/zhmcclient/zhmc-ansible-modules/jobs/431432871
 #    - os: osx
 #      language: generic
 #      python: