chore: upgrade composer deps & use pcov

Also let travis know of the stuff.

Author: swashata

.travis.yml

@@ -1,9 +1,11 @@
 language: php
 php:
-  - '7.2'
+  - '7.3'
 before_script:
+  - pecl install pcov
   - npm i -g codecov
   - composer install
+  - ./vendor/bin/pcov clobber
 script:
   - composer run-script lint
   - composer run-script test

composer.json

@@ -17,7 +17,8 @@
       "spatie/phpunit-snapshot-assertions": "^1.3.1",
       "phpunit/phpunit": "^7.3.0",
       "brain/monkey": "^2.2.0",
-      "giacocorsiglia/wordpress-stubs": "^4.9.5"
+      "giacocorsiglia/wordpress-stubs": "^4.9.5",
+        "pcov/clobber": "^2.0"
     },
     "autoload": {
       "psr-4": {