Update taiki-e/install-action digest to c6dc131 (#182)

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@32a9cb44cba26910c999123dfe4a4e0e07b08f12 # v2
+        uses: taiki-e/install-action@c6dc131d2c4291552cafb840290190a53b2cd937 # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme