fix(ci): grant callers the permissions their reusable workflows declare (#132)

GitHub refuses these runs at workflow-creation time: `Error calling
workflow ... The workflow is requesting '<perm>', but is only allowed
'<none>'.` A `workflow_call` job must grant a superset of the callee's
declared permissions. This adds the canonical grant (`actions: read`,
`contents: read`, `security-events: write`) that the healthy repos
already carry.

Author: hyperpolymath

.github/workflows/governance.yml

@@ -18,3 +18,7 @@ permissions:
 jobs:
   governance:
     uses: hyperpolymath/standards/.github/workflows/governance-reusable.yml@fad242d35291de1898242d6737ba02b74a59a2f2
+      permissions:
+        actions: read
+        contents: read
+        security-events: write

.github/workflows/mirror.yml

@@ -17,3 +17,7 @@ jobs:
   mirror:
     uses: hyperpolymath/standards/.github/workflows/mirror-reusable.yml@bd0df9ead7faf0cdfe0e13e7966d91e28d0101d4
     secrets: inherit
+      permissions:
+        actions: read
+        contents: read
+        security-events: write

.github/workflows/scorecard.yml

@@ -19,6 +19,7 @@ jobs:
   scorecard:
     uses: hyperpolymath/standards/.github/workflows/scorecard-reusable.yml@bd0df9ead7faf0cdfe0e13e7966d91e28d0101d4
     permissions:
+      actions: read
       contents: read
       security-events: write
       id-token: write

.github/workflows/secret-scanner.yml

@@ -20,6 +20,7 @@ permissions:
 jobs:
   scan:
     permissions:
+      security-events: write
       contents: read
       pull-requests: write
       actions: read