fix(ci): grant callers the permissions their reusable workflows declare (#556)

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

@@ -36,3 +36,7 @@ permissions:
 jobs:
   governance:
     uses: hyperpolymath/standards/.github/workflows/governance-reusable.yml@da2c748aad55c1a1dcba00b60fe4a35017bc6540
+      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@571cc734cd69fb846032ec77a662aa8ee4fc32cd
     secrets: inherit
+      permissions:
+        actions: read
+        contents: read
+        security-events: write

.github/workflows/scorecard.yml

@@ -14,6 +14,7 @@ permissions:
 jobs:
   scorecard:
     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