fix(ci): grant callers the permissions their reusable workflows declare (#33)

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

@@ -35,3 +35,7 @@ permissions:
 jobs:
   governance:
     uses: hyperpolymath/standards/.github/workflows/governance-reusable.yml@84355587cb2a1f86e6882de83514a32db2646e7a
+      permissions:
+        actions: read
+        contents: read
+        security-events: write

.github/workflows/secret-scanner.yml

@@ -21,3 +21,7 @@ jobs:
   secret-scan:
     uses: hyperpolymath/standards/.github/workflows/secret-scanner-reusable.yml@bd0df9ead7faf0cdfe0e13e7966d91e28d0101d4
     secrets: inherit
+      permissions:
+        actions: read
+        contents: read
+        security-events: write