ci: update node versions in GitHub Actions workflow

Replace Node.js 14 with 20 in CI matrix configurations.

Issue: BTC-2285

Co-authored-by: llm-git <llm-git@ttll.de>

Author: davidkaplanbitgo

.github/workflows/main_ci.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [14, 16]
+        node-version: [16, 20]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
@@ -36,7 +36,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [14, 16]
+        node-version: [16, 20]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
     services:
       regtest: