Set adequate permissions to push benchmarks

.github/workflows/bench-primitives.yml

@@ -1,5 +1,8 @@
 name: rosenpass-ciphers - primitives - benchmark
 
+permissions:
+  contents: write
+
 on:
   pull_request:
   push:

.github/workflows/bench-protocol.yml

@@ -1,5 +1,8 @@
 name: rosenpass - protocol - benchmark
 
+permissions:
+  contents: write
+
 on:
   pull_request:
   push: