chore(awgen): bump 0.2 -> 0.3

Upstream tagged v0.3 (3d10c5f) in alex/awgen. The dependency set is
unchanged, so cargoHash stays the same; only the source hash needed a
recompute for the new tag.

Verified: nix build .#awgen is green, cargo checkPhase reports 29 passed
/ 0 failed, and the resulting binary runs. Upstream Cargo.toml still
declares 0.1.0, so `awgen --version` prints 0.1.0 while the derivation
version (taken from the tag) is 0.3.

packages/awgen/package.nix

@@ -6,14 +6,14 @@
 
 rustPlatform.buildRustPackage rec {
   pname = "awgen";
-  version = "0.2";
+  version = "0.3";
 
   src = fetchFromGitea {
     domain = "git.millerson.name";
     owner = "alex";
     repo = "awgen";
     rev = "v${version}";
-    hash = "sha256-hW8QONvwvhBcg2aHzOO1SNpLF7I+As4dxdYodGYHPUw=";
+    hash = "sha256-86YTRYXiCpGQ1PkbGhYIwBwTMcO7ffZDla9PNFtrhIE=";
   };
 
   cargoHash = "sha256-Y7SKh0F7wOTejBesjQbLVBoZKjDDrVGUjGCVZRlP4lg=";