Try to fix CI test

Author: svenstaro

.github/workflows/ci.yml

@@ -41,7 +41,7 @@ jobs:
           const fs = require('fs')
           const assert = require('assert').strict;
 
-          const expected = fs.readFileSync("README.md", "utf-8")
+          const expected = fs.readFileSync("README.md", "utf8")
           const release = await github.rest.repos.getReleaseByTag({
             ...context.repo,
             tag: "ci-test-${{ matrix.os }}-${{ github.run_id }}",
@@ -72,7 +72,7 @@ jobs:
           const fs = require('fs')
           const assert = require('assert').strict;
           
-          const expected = fs.readFileSync("README.md", "utf-8")
+          const expected = fs.readFileSync("README.md", "utf8")
           const release = await github.rest.repos.getReleaseByTag({
             ...context.repo,
             tag: "ci-test-${{ matrix.os }}-${{ github.run_id }}",