Update taiki-e/install-action digest to 7b20dfd (#275)

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@92f69c195229fe62d58b4d697ab4bc75def98e76 # v2
+        uses: taiki-e/install-action@7b20dfd705618832f20d29066e34aa2f2f6194c2 # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme