v0.3.0

Added

• Adds a new middleware to publish message metrics
• Adds thread safety to MessageAttributes in MessageEvent
• Adds a metric to measure the handlerFunc exec time
• Adds a make task to start the app
• Adds a make task to start-up the metrics containers
• Adds a make task to produce messages to kafka

Changes

• halts the app if retries are disabled, and a message is retried
• changes the --zigurat-config to -config
• app.Run accepts a zig.RunOptions type
• fixes race conditions when starting-up the app
• uses constructors functions to initialize components