Set GitHub actions permissions explicitly

Author: matze

.github/workflows/release.yml

@@ -2,6 +2,9 @@ on:
   release:
     types: [created]
 
+permissions:
+  contents: write
+
 jobs:
   release:
     name: Release on ${{ matrix.target }}

.github/workflows/rust.yml

@@ -2,6 +2,9 @@ name: Rust
 
 on: [push, pull_request]
 
+permissions:
+  contents: read
+
 env:
   CARGO_TERM_COLOR: always