Update taiki-e/install-action digest to a209ff0 (#219)

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@3c8fc6eaa5fcff049bb133c1f540c6c2287a191f # v2
+        uses: taiki-e/install-action@a209ff0ce0349f9e7cadc4ba8f6a415c8d3b0813 # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme