Objective-C Tracker: bump git submodule to 0.6.1 (close #2709)
Objective-C Tracker: bump git submodule to 0.6.1 (close #2709)

snowplow/snowplow,TimothyKlim/snowplow,liveintent-berlin/snowplow,simplybusiness/snowplow-fork,simplybusiness/snowplow-fork,aldemirenes/snowplow,Propertyfinder/snowplow,chuwy/snowplow-ci,RetentionGrid/snowplow,nakulgan/snowplow,RajeshHegde/snowplow,bigdecisions/snowplow,acgray/snowplow,RajeshHegde/snowplow,bigdecisions/snowplow,chuwy/snowplow-ci,sspinc/snowplow,Propertyfinder/snowplow,sspinc/snowplow,haensel-ams/snowplow,Propertyfinder/snowplow,liveintent-berlin/snowplow,Propertyfinder/snowplow,TimothyKlim/snowplow,nakulgan/snowplow,aldemirenes/snowplow,chuwy/snowplow-ci,acgray/snowplow,atotech/snowplow,atotech/snowplow,nakulgan/snowplow,atotech/snowplow,sspinc/snowplow,nakulgan/snowplow,bigdecisions/snowplow,simplybusiness/snowplow-fork,simplybusiness/snowplow-fork,liveintent-berlin/snowplow,RetentionGrid/snowplow,snowplow/snowplow,TimothyKlim/snowplow,nakulgan/snowplow,aldemirenes/snowplow,RajeshHegde/snowplow,haensel-ams/snowplow,RetentionGrid/snowplow,acgray/snowplow,haensel-ams/snowplow,haensel-ams/snowplow,liveintent-berlin/snowplow,acgray/snowplow,liveintent-berlin/snowplow,sspinc/snowplow,RajeshHegde/snowplow,sspinc/snowplow,haensel-ams/snowplow,atotech/snowplow,chuwy/snowplow-ci,snowplow/snowplow,acgray/snowplow,acgray/snowplow,Propertyfinder/snowplow,TimothyKlim/snowplow,aldemirenes/snowplow,atotech/snowplow,snowplow/snowplow,Propertyfinder/snowplow,aldemirenes/snowplow,bigdecisions/snowplow,RetentionGrid/snowplow,atotech/snowplow,liveintent-berlin/snowplow,RajeshHegde/snowplow,RetentionGrid/snowplow,bigdecisions/snowplow,sspinc/snowplow,simplybusiness/snowplow-fork,nakulgan/snowplow,chuwy/snowplow-ci,TimothyKlim/snowplow,chuwy/snowplow-ci,RajeshHegde/snowplow,simplybusiness/snowplow-fork,haensel-ams/snowplow,bigdecisions/snowplow,aldemirenes/snowplow