Update taiki-e/install-action digest to a50f5c5 (#306)

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@f37a1e4d34f3e1c6a571e294b0258f2805eab48d # v2
+        uses: taiki-e/install-action@a50f5c566832c96fba2012b0d5fe60c3669d7812 # v2
         with:
           tool: cargo-readme
       - name: Run cargo readme