Minimal token permissions

See tokio-rs/tokio#5072

Author: jonhoo

.github/workflows/check.yml

@@ -1,3 +1,5 @@
+permissions:
+  contents: read
 on:
   push:
     branches: [main]

.github/workflows/nostd.yml

@@ -1,3 +1,5 @@
+permissions:
+  contents: read
 on:
   push:
     branches: [main]

.github/workflows/safety.yml

@@ -1,3 +1,5 @@
+permissions:
+  contents: read
 on:
   push:
     branches: [main]

.github/workflows/scheduled.yml

@@ -1,3 +1,5 @@
+permissions:
+  contents: read
 on:
   push:
     branches: [main]

.github/workflows/test.yml

@@ -1,3 +1,5 @@
+permissions:
+  contents: read
 on:
   push:
     branches: [main]