FIX(CI): Only run CI on source and .toml changes

There is no need to rerun CI if only the README has changed

.github/workflows/build.yml

@@ -4,7 +4,13 @@ on:
   push:
     branches:
       - '**'
+    paths:
+      - '**/*.rs'
+      - '**/*.toml'
   pull_request:
+    paths:
+      - '**/*.rs'
+      - '**/*.toml'
 
 jobs:
   install-cross:
@@ -104,4 +110,4 @@ jobs:
         channel: [ stable, beta ]
         target:
           - x86_64-unknown-linux-gnu
-          - x86_64-unknown-linux-musl
+          - x86_64-unknown-linux-musl