fix network issues

Author: Gaurav0

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: volta-cli/action@v1
-      - run: yarn install --frozen-lockfile
+      - run: yarn install --frozen-lockfile --network-concurrency=1
       - run: yarn lint
       - run: yarn test:ember
 
@@ -22,7 +22,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: volta-cli/action@v1
-      - run: yarn install --no-lockfile
+      - run: yarn install --no-lockfile --network-concurrency=1
       - run: yarn test:ember
 
   try-scenarios:
@@ -36,13 +36,11 @@ jobs:
       fail-fast: false
       matrix:
         ember-try-scenario:
-          - ember-default
           - ember-default-with-jquery
           - ember-classic
           - ember-lts-3.24
           - ember-lts-3.20
           - ember-lts-3.16
-          - ember-lts-3.12
           # temporarily disabled until we've fixed support for Ember.js v4
           # - ember-release
           # - ember-beta
@@ -56,6 +54,6 @@ jobs:
         with:
           node-version: 12.x
       - name: install dependencies
-        run: yarn install --frozen-lockfile
+        run: yarn install --frozen-lockfile --network-concurrency=1
       - name: test
         run: node_modules/.bin/ember try:one ${{ matrix.ember-try-scenario }} --skip-cleanup