Update taiki-e/install-action digest to 42f4ec8

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@05515455a9007c7c6f0b215637566ab8e9872c12 # v2
+        uses: taiki-e/install-action@42f4ec8e42bf7fe4dadd39bfc534566095a8edff # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme