Don't allow swift grpc generation on swift.

Swift on Windows isn't great atm.

car/build.gradle

@@ -16,7 +16,8 @@ task copyPythonCode(type: Copy, dependsOn: configurations.python){
 }
 
 task build(type: Exec, dependsOn: copyPythonCode) {
-    commandLine 'python3', 'setup.py', 'bdist_wheel'
+    executable 'python3'
+    args 'setup.py', 'bdist_wheel'
 }
 
 task clean {

car/requirements.txt

@@ -6,3 +6,4 @@ u-msgpack-python
 grpcio-tools
 rplidar
 pyzmq
+wheel

protobuf/build.gradle

@@ -22,19 +22,21 @@ configurations {
 protobuf {
     protoc { artifact = 'com.google.protobuf:protoc:3.11.0' }
     plugins {
-        swift {
-            path = "$projectDir/grpc_plugins/protoc-gen-swift"
-        }
         grpc {
             artifact = 'io.grpc:protoc-gen-grpc-java:1.28.1' // CURRENT_GRPC_VERSION
         }
         grpc_python {
             path = "$projectDir/grpc_plugins/grpc_python_plugin_1.28.1-${osdetector.classifier}"
         }
+        if(osdetector.os != 'windows'){
+            swift {
+                path = "$projectDir/grpc_plugins/protoc-gen-swift"
+            }
             grpc_swift {
                 path = "$projectDir/grpc_plugins/protoc-gen-grpc-swift-$osdetector.classifier"
             }
         }
+    }
     generateProtoTasks {
         all().each { task ->
             task.builtins {
@@ -43,19 +45,21 @@ protobuf {
                 python {}
             }
             task.plugins {
-                swift{}
                 grpc { // Options added to --grpc_out
                     option 'lite'
                 }
                 grpc_python {
                     outputSubDir = 'python'
                 }
+                if(osdetector.os != 'windows'){
+                    swift{}
                     grpc_swift {
                         outputSubDir = 'swift'
                     }
                 }
             }
         }
+    }
 }
 
 task packPythonGrpc(type: Zip, dependsOn: protobuf.generateProtoTasks.all()) {