Include Carthage in PMKiOSCategoryTests search paths

Test target could not run. See:
Carthage/Carthage#1002

Author: nathanhosselton

PromiseKit.xcodeproj/project.pbxproj

@@ -1918,7 +1918,7 @@
 					"$(inherited)",
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 8.3;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks $(PROJECT_DIR)/Carthage/Build/iOS";
 				PRODUCT_BUNDLE_IDENTIFIER = "org.promisekit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = Tests/Categories/bridge.h;
@@ -1937,7 +1937,7 @@
 				);
 				GCC_NO_COMMON_BLOCKS = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 8.3;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks $(PROJECT_DIR)/Carthage/Build/iOS";
 				PRODUCT_BUNDLE_IDENTIFIER = "org.promisekit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = Tests/Categories/bridge.h;