chore(CI): bump pnpm version up to 8

Author: yamatatsu

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         name: Install pnpm
         id: pnpm-install
         with:
-          version: 7
+          version: 8
           run_install: false
       - run: pnpm install
       - run: pnpm test run

.github/workflows/release.yml

@@ -29,7 +29,7 @@ jobs:
         name: Install pnpm
         id: pnpm-install
         with:
-          version: 7
+          version: 8
           run_install: false
       - run: pnpm install
       - run: pnpm test run