tweak the opt level for dev profile.

Cargo.toml

@@ -27,3 +27,11 @@ heron = { path = "../heron/" }
 
 [patch."https://github.com/bevyengine/bevy"]
 bevy = { path = "../bevy/" }
+
+# Enable optimizations for dependencies (incl. Bevy), but not for our code:
+[profile.dev.package."*"]
+opt-level = 3
+
+# Maybe also enable only a small amount of optimization for our code:
+[profile.dev]
+opt-level = 1