Eliminate invokables from test data.

module/VuFindTheme/tests/unit-tests/fixtures/themes/child/theme.config.php

@@ -7,7 +7,7 @@ return [
         'factories' => [
             'foo' => 'fooOverrideFactory',
         ],
-        'invokables' => [
+        'aliases' => [
             'xyzzy' => 'Xyzzy',
         ]
     ],

module/VuFindTheme/tests/unit-tests/src/VuFindTest/ThemeCompilerTest.php

@@ -128,7 +128,7 @@ class ThemeCompilerTest extends Unit\TestCase
                     'foo' => 'fooOverrideFactory',
                     'bar' => 'barFactory',
                 ],
-                'invokables' => [
+                'aliases' => [
                     'xyzzy' => 'Xyzzy',
                 ]
             ],
@@ -186,7 +186,7 @@ class ThemeCompilerTest extends Unit\TestCase
                     'foo' => 'fooOverrideFactory',
                     'bar' => 'barFactory',
                 ],
-                'invokables' => [
+                'aliases' => [
                     'xyzzy' => 'Xyzzy',
                 ]
             ],