build: align minimum build dependencies with ndn-cxx

 * gcc 7.4
 * clang 6.0
 * Xcode 10.0 (11.3 or later recommended)

Also update waf to version 2.0.23

Change-Id: Ic8180b88df8c95c0d416ef308046f8e7ff79d26a
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 7e19491..f27285b 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -21,7 +21,7 @@
       WAF_JOBS: 3
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install dependencies
         run: |
           case ${RUNNER_OS} in