Use I try for the update steps of the prefetch scenarios

`I run` fails on any STDERR output as well as on a non-zero exit, and
the neighbouring `update --all` scenarios use `I try` for that reason.
The theme scenario is tagged @require-wp-4.5 like the one before it.

Author: austinginder

features/plugin-update.feature

@@ -383,7 +383,7 @@ Feature: Update WordPress plugins
     When I run `wp plugin install wordpress-importer --version=0.5`
     Then STDOUT should not be empty
 
-    When I run `wp plugin update --all`
+    When I try `wp plugin update --all`
     Then STDOUT should contain:
       """
       Downloading 2 packages...
@@ -399,7 +399,7 @@ Feature: Update WordPress plugins
 
     When I run `wp plugin install health-check --version=1.5.0 --force`
     And I run `wp plugin install wordpress-importer --version=0.5 --force`
-    And I run `wp plugin update --all`
+    And I try `wp plugin update --all`
     Then STDOUT should not contain:
       """
       Downloading 2 packages...
@@ -418,7 +418,7 @@ Feature: Update WordPress plugins
     When I run `wp plugin install wordpress-importer --version=0.5`
     Then STDOUT should not be empty
 
-    When I run `wp plugin update --all`
+    When I try `wp plugin update --all`
     Then STDOUT should not contain:
       """
       Downloading 1 packages...

features/theme-update.feature

@@ -258,6 +258,7 @@ Feature: Update WordPress themes
       Success: Updated 2 of 2 themes.
       """
 
+  @require-wp-4.5
   Scenario: Updating several themes downloads their packages side by side
     Given a WP install
     And an empty cache
@@ -269,7 +270,7 @@ Feature: Update WordPress themes
     When I run `wp theme install twentytwelve --version=1.0`
     Then STDOUT should not be empty
 
-    When I run `wp theme update --all`
+    When I try `wp theme update --all`
     Then STDOUT should contain:
       """
       Downloading 2 packages...