Pin Rust crate insta to =1.43.2

Author: renovate[bot]

crates/plotnik-lib/Cargo.toml

@@ -8,4 +8,4 @@ logos = "0.15.1"
 serde = { version = "1.0.228", features = ["derive"] }
 
 [dev-dependencies]
-insta = { version = "1.43.2", features = ["yaml"] }
+insta = { version = "=1.43.2", features = ["yaml"] }