Aptly Release 1.6.1

Changes

• update golang-github-syndtr-goleveldb-dev dependency (v1.0.1-0.20220721030215-126854af5e6d) to fix segfault on arm64
  (bug in golang-github-golang-snappy-dev) #1172
• allow snapshotting empty mirrors again (regression) #1416
• debian compliance: add postrm (note: apt purge aptly-api will remove all data in ~aptly-api/) #1425
• update other dependencies (x/net 0.33.0, gin-gonic/gin 1.9.1, x/crypto 0.31.0) #1420 #1187 #1407