Update PythonRuntimeTests.swift

Author: philipturner

Tests/PythonKitTests/PythonRuntimeTests.swift

@@ -328,6 +328,12 @@ class PythonRuntimeTests: XCTestCase {
     }
 
     func testPythonFunction() {
+        let versionMajor = Python.versionInfo.major
+        let versionMinor = Python.versionInfo.minor
+        guard (versionMajor == 3 && versionMinor >= 1) || versionMajor > 3 else {
+            return
+        }
+        
         let pythonAdd = PythonFunction { (params: [PythonObject]) in
             let lhs = params[0]
             let rhs = params[1]