Merge branch 'hotfix/v0.1.1'
Merge branch 'release/wechat-python-sdk-v0.2'
Merge branch 'release/wechat-python-sdk-v0.2.3'
Merge branch 'release/wechat-python-sdk-v0.2.4'
Merge branch 'release/wechat-python-sdk-v0.2.5'
Merge branch 'release/wechat-python-sdk-v0.2.6'
Merge branch 'release/wechat-python-sdk-v0.2.7'
Merge branch 'release/wechat-python-sdk-v0.3'
Merge branch 'release/wechat-python-sdk-v0.3.1'
Merge branch 'release/wechat-python-sdk-v0.3.2'
Merge branch 'release/wechat-python-sdk-v0.3.3'
Merge branch 'release/wechat-python-sdk-v0.3.4'
Merge branch 'release/wechat-python-sdk-v0.3.5'
Merge branch 'release/wechat-python-sdk-v0.3.6'
Merge branch 'release/wechat-python-sdk-v0.3.7'
Merge branch 'release/wechat-python-sdk-v0.3.8'
Merge branch 'release/wechat-python-sdk-v0.4.0'
Merge branch 'release/v0.4.1'
Merge branch 'release/v0.4.2'
Add VoiceMessage Recognition check default value.

For those empty VoiceMessage, they are useless, but perfectly legal.