remove php 7.0 supporting

Author: tyron

.travis.yml

@@ -1,8 +1,8 @@
 language: php
 php:
-    - 7
     - 7.1
     - 7.2
+    - 7.3
 
 env:
   - CLICKHOUSE_VERSION=latest
@@ -18,4 +18,4 @@ before_script:
     - docker run -d -p 127.0.0.1:8123:8123 --name test-clickhouse-server --ulimit nofile=262144:262144 yandex/clickhouse-server:$CLICKHOUSE_VERSION
     - docker logs test-clickhouse-server
 
-script: ./vendor/bin/phpunit
+script: ./vendor/bin/phpunit

composer.json

@@ -5,7 +5,7 @@
     "type": "yii2-extension",
     "license": "MIT",
     "require": {
-        "php": ">=7.0",
+        "php": "^7.1",
         "yiisoft/yii2": "~2.0.13",
         "smi2/phpclickhouse": "^1.3.3"
     },