Tweak GitHub Actions workflows (#133)

- Remove Corepack env var per seek-oss/skuba#1789
- Add `checks` permission that other `seek-oss` repos seem to set

Author: 72636c

.github/workflows/release.yml

@@ -5,9 +5,6 @@ on:
     branches:
       - main
 
-env:
-  COREPACK_DEFAULT_TO_LATEST: 0
-
 permissions: {}
 
 jobs:

.github/workflows/snapshot.yml

@@ -2,9 +2,6 @@ name: Snapshot
 
 on: workflow_dispatch
 
-env:
-  COREPACK_DEFAULT_TO_LATEST: 0
-
 permissions: {}
 
 jobs:

.github/workflows/validate.yml

@@ -15,14 +15,13 @@ on:
     workflows:
       - Release
 
-env:
-  COREPACK_DEFAULT_TO_LATEST: 0
-
 permissions: {}
 
 jobs:
   core:
     name: Lint & Test
+    permissions:
+      checks: write
     runs-on: ubuntu-latest
     steps:
       - name: Check out repo