Update taiki-e/install-action digest to 81ee1d4 (#384)

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@47be02f2de8a32619316956f6117e150bdc6763f # v2
+        uses: taiki-e/install-action@81ee1d48d9194cdcab880cbdc7d36e87d39874cb # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme