chore(package): update testem to version 1.6.0
chore(package): update testem to version 1.6.0

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bustle/mobiledoc-kit,bustlelabs/content-kit-editor,mixonic/content-kit-editor,Hstry/mobiledoc-kit,YoranBrondsema/mobiledoc-kit,bustlelabs/content-kit-editor,bustle/mobiledoc-kit,atonse/mobiledoc-kit,bustlelabs/mobiledoc-kit,mixonic/content-kit-editor,Hstry/mobiledoc-kit,YoranBrondsema/mobiledoc-kit,bustlelabs/content-kit-editor,Hstry/mobiledoc-kit,atonse/mobiledoc-kit,atonse/mobiledoc-kit,bustlelabs/mobiledoc-kit,bustle/mobiledoc-kit,bustlelabs/mobiledoc-kit,YoranBrondsema/mobiledoc-kit,bustle/mobiledoc-kit,mixonic/content-kit-editor