Appveyor runs php7.3 now. (#158)

* Appveyor runs php7.3 now.

* Update README.md

Author: Nyholm

README.md

@@ -297,7 +297,7 @@ install:
   - ps: Set-Service wuauserv -StartupType Manual
   - cinst -y php composer googlechrome
   - refreshenv
-  - cd c:\tools\php72
+  - cd c:\tools\php73
   - copy php.ini-production php.ini /Y
   - echo date.timezone="UTC" >> php.ini
   - echo extension_dir=ext >> php.ini

appveyor.yml

@@ -9,7 +9,7 @@ install:
   - ps: Set-Service wuauserv -StartupType Manual
   - cinst -y php composer googlechrome
   - refreshenv
-  - cd c:\tools\php72
+  - cd c:\tools\php73
   - copy php.ini-production php.ini /Y
   - echo date.timezone="UTC" >> php.ini
   - echo extension_dir=ext >> php.ini