v0.9.0

ProtoBuf v0.9.0

Diff since v0.8.0

Closed issues:

• SerializeToString method for Protobuf.jl (#125)
• 0.7.0 doesn't work with Julia 1.3 (#134)
• Make ProtoBuf thread safe (#140)

Merged pull requests:

• update Project.toml for tagging (#135) (@tanmaykm)
• Install TagBot as a GitHub Action (#136) (@JuliaTagBot)
• update package and code generator for thread safety, few other improvements (#141) (@tanmaykm)