ci: remove Node@8

Author: hiroppy

azure-pipelines.yml

@@ -52,9 +52,6 @@ jobs:
         node-10:
           node_version: ^10.13.0
           webpack_version: latest
-        node-8:
-          node_version: ^8.9.0
-          webpack_version: latest
         node-10-canary:
           node_version: ^10.13.0
           webpack_version: next
@@ -108,9 +105,6 @@ jobs:
         node-10:
           node_version: ^10.13.0
           webpack_version: latest
-        node-8:
-          node_version: ^8.9.0
-          webpack_version: latest
         node-10-canary:
           node_version: ^10.13.0
           webpack_version: next
@@ -164,9 +158,6 @@ jobs:
         node-10:
           node_version: ^10.13.0
           webpack_version: latest
-        node-8:
-          node_version: ^8.9.0
-          webpack_version: latest
         node-10-canary:
           node_version: ^10.13.0
           webpack_version: next