Add .pt2 extension (#1211)

package.json

@@ -154,6 +154,7 @@
             { "ext": "pkl",         "name": "Pickle Model"             },
             { "ext": "prototxt",    "name": "Text Protocol Buffer"     },
             { "ext": "pt",          "name": "PyTorch Model"            },
+            { "ext": "pt2",         "name": "PyTorch Model"            },
             { "ext": "pth",         "name": "PyTorch Model"            },
             { "ext": "ptl",         "name": "PyTorch Model"            },
             { "ext": "rknn",        "name": "RKNN Model"               },

source/base.js

@@ -1160,7 +1160,7 @@ base.Metadata = class {
 
     get extensions() {
         return [
-            'onnx', 'tflite', 'pb', 'pt', 'pth', 'h5', 'pbtxt', 'prototxt', 'caffemodel', 'mlmodel', 'mlpackage',
+            'onnx', 'tflite', 'pb', 'pt', 'pt2', 'pth', 'h5', 'pbtxt', 'prototxt', 'caffemodel', 'mlmodel', 'mlpackage',
             'model', 'json', 'xml', 'cfg', 'bin',
             'ort',
             'dnn', 'cmf',