tests: bumped Node versions for testing (#4451)

.github/workflows/generate-docs.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v1
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Checkout repository
         uses: actions/checkout@v3

.github/workflows/test-browser.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Install Node.js
         uses: actions/setup-node@v1
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Install and run Geth
         uses: ethers-io/run-geth-action@main

.github/workflows/test-ci.yml

@@ -25,7 +25,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [ 16.x, 18.x ]
+        node-version: [ 18.x, 20.x ]
         test-type: [ esm, commonjs ]
 
     steps:
@@ -66,7 +66,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v1
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Install and run Geth
         uses: ethers-io/run-geth-action@main

.github/workflows/test-env.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Use Node.js
         uses: actions/setup-node@v1
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Checkout repository
         uses: actions/checkout@v3
@@ -65,7 +65,7 @@ jobs:
       - name: Use Node.js
         uses: actions/setup-node@v1
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Checkout repository
         uses: actions/checkout@v3