Fix tests

Author: STREGA

Tests/GateEngineTests/Gravity/GravityCreateValueTests.swift

@@ -9,6 +9,7 @@
 import XCTest
 @testable import GateEngine
 
+@MainActor
 final class GravityCreateValueTests: GateEngineXCTestCase {
     let gravity = Gravity()
     func testInt() {

Tests/GateEngineTests/Gravity/GravityErrorTests.swift

@@ -9,6 +9,7 @@
 import XCTest
 @testable import GateEngine
 
+@MainActor
 final class GravityErrorTests: GateEngineXCTestCase {
     var gravity: Gravity! = nil
     var randomValue: Int = 0

Tests/GateEngineTests/Gravity/GravityExtendingTests.swift

@@ -9,6 +9,7 @@
 import XCTest
 @testable import GateEngine
 
+@MainActor
 final class GravityExtendingTests: GateEngineXCTestCase {
     var gravity: Gravity! = nil
     var randomValue: Int = 0

Tests/GateEngineTests/Gravity/GravityIncludesTests.swift

@@ -10,6 +10,7 @@ import XCTest
 @testable import GateEngine
 
 // These tests make sure multiple instances of `Gravity` can co-exist.
+@MainActor
 final class GravityIncludesTests: GateEngineXCTestCase {
     func testIncludes() async throws {
         let gravity = Gravity()

Tests/GateEngineTests/Gravity/GravityMultipleInstanceTests.swift

@@ -9,6 +9,7 @@
 import XCTest
 @testable import GateEngine
 
+@MainActor
 final class GravityMultipleInstanceTests: GateEngineXCTestCase {
     func testMultipleInstanceSetVar() throws {
         let script = "extern var myVar; func main() {return myVar}"

Tests/GravityTests/_GravityXCTestCase.swift

@@ -10,6 +10,7 @@ import XCTest
 @testable import GateEngine
 @testable import Gravity
 
+@MainActor
 open class GravityXCTestCase: XCTestCase {
     func runGravity(at path: String) async {
         let gravity = Gravity()