Update taiki-e/install-action digest to 9bef7e9

Author: nextest-bot

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Lint (rustfmt)
         run: cargo xfmt --check
       - name: Install cargo readme
-        uses: taiki-e/install-action@47e2e5cbd7dd21055d49e9c71d8508cb12a9f895 # v2
+        uses: taiki-e/install-action@9bef7e9c3d7c7aa986ef19933b0722880ae377e0 # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme