#712 Update appveyor [skip travis]

Signed-off-by: Uilian Ries <uilianries@gmail.com>

appveyor.yml

@@ -13,15 +13,16 @@ skip_commits:
   files:
   - '**/*.md'
 
-environment:
-  PYTHON: "C:\\Python37"
-  matrix:
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      CONAN_VISUAL_VERSIONS: 12
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      CONAN_VISUAL_VERSIONS: 14
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      CONAN_VISUAL_VERSIONS: 15
+matrix:
+  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    CONAN_VISUAL_VERSIONS: 12
+    PYTHON: "C:\\Python37"
+  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    CONAN_VISUAL_VERSIONS: 14
+    PYTHON: "C:\\Python37"
+  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    CONAN_VISUAL_VERSIONS: 15
+    PYTHON: "C:\\Python37"
   install:
     - set PATH=%PATH%;%PYTHON%/Scripts/
     - pip.exe install conan conan_package_tools