fix: drop node 8 support

Author: mihar-22

.travis.yml

@@ -7,9 +7,9 @@ cache:
 notifications:
   email: false
 node_js:
-  - '8'
   - '10'
   - '12'
+  - '14'
 env:
   global:
     - PATH=$HOME/.yarn/bin:$PATH

package.json

@@ -15,7 +15,7 @@
     "url": "https://github.com/testing-library/preact-testing-library/issues"
   },
   "engines": {
-    "node": ">= 8"
+    "node": ">= 10"
   },
   "keywords": [
     "testing",