Add autometrics 0.3 blog post

Author: emschwartz

draft/2023-03-22-this-week-in-rust.md

@@ -34,6 +34,7 @@ and just ask the editors to select the category.
 ### Newsletters
 
 ### Project/Tooling Updates
+* [autometrics 0.3: Defining Service-Level Objectives (SLOs) in Rust Source Code](https://fiberplane.com/blog/autometrics-rs-v0-3-defining-service-level-objectives-in-rust-source-code)
 
 ### Observations/Thoughts