[Tests] test node 15, 16 on appveyor

Author: ljharb

appveyor.yml

@@ -4,7 +4,9 @@ build: off
 
 environment:
   matrix:
-    #- nodejs_version: "15"
+    #- nodejs_version: "17"
+    - nodejs_version: "16"
+    - nodejs_version: "15"
     - nodejs_version: "14"
     - nodejs_version: "13"
     - nodejs_version: "12"
@@ -59,6 +61,7 @@ install:
   - IF %nodejs_version% EQU 13 npm -g install npm@7
   - IF %nodejs_version% EQU 14 npm -g install npm@7
   - IF %nodejs_version% EQU 15 npm -g install npm@7
+  - IF %nodejs_version% EQU 16 npm -g install npm@7
   - set PATH=%APPDATA%\npm;%PATH%
   #- IF %nodejs_version% NEQ 0.6 AND %nodejs_version% NEQ 0.8 npm -g install npm
   # install modules