Add kokoro_duration_t128 for v1.6.1 enumerated-token duration models

coreml/kokoro_duration_t128.mlpackage/Data/com.apple.CoreML/model.mlmodel

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+oid sha256:f573d756579e385b9e733882e2a89721a9f45844cf1a590f01dcd2d3d2fdea36
+size 5540359

coreml/kokoro_duration_t128.mlpackage/Data/com.apple.CoreML/weights/weight.bin

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+version https://git-lfs.github.com/spec/v1
+oid sha256:25db30a2ec864db6b048ce149e980a42dbc9ee2b29fdb8ca956b5a0e8289f1ee
+size 38918912

coreml/kokoro_duration_t128.mlpackage/Manifest.json

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+{
+    "fileFormatVersion": "1.0.0",
+    "itemInfoEntries": {
+        "5F93D794-ABB4-482D-9ABF-42A892412539": {
+            "author": "com.apple.CoreML",
+            "description": "CoreML Model Specification",
+            "name": "model.mlmodel",
+            "path": "com.apple.CoreML/model.mlmodel"
+        },
+        "904F1D24-3C95-4AB2-8C02-B94EC2697E04": {
+            "author": "com.apple.CoreML",
+            "description": "CoreML Model Weights",
+            "name": "weights",
+            "path": "com.apple.CoreML/weights"
+        }
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+    "rootModelIdentifier": "5F93D794-ABB4-482D-9ABF-42A892412539"
+}