Bump Tarantool and tools versions in tests

Based on PR #18 by @no1seman

Author: no1seman

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: tarantool/setup-tarantool@v1
         with:
-          tarantool-version: '2.7'
+          tarantool-version: '2.8'
 
       - run: echo "TAG=${GITHUB_REF##*/}" >> $GITHUB_ENV
       - run: tarantoolctl rocks new_version --tag $TAG

.github/workflows/test_on_push.yaml

@@ -11,7 +11,7 @@ jobs:
       github.event_name == 'pull_request' && github.event.pull_request.head.repo.owner.login != 'tarantool'
     strategy:
       matrix:
-        tarantool-version: ["1.10", "2.7"]
+        tarantool-version: ["1.10", "2.8"]
       fail-fast: false
     runs-on: [ubuntu-20.04]
     steps:
@@ -22,8 +22,8 @@ jobs:
 
       - name: Install dependencies
         run: |
-          tarantoolctl rocks install luatest 0.5.2
-          tarantoolctl rocks install luacheck 0.25.0
+          tarantoolctl rocks install luatest 0.5.5
+          tarantoolctl rocks install luacheck 0.26.0
           tarantoolctl rocks make
 
       - name: Run linter