Update to fix error when using with transformers

The following code breaks without this change:
```
text_encoder = CLIPTextModelWithProjection.from_pretrained("laion/CLIP-ViT-bigG-14-laion2B-39B-b160k")
```

config.json

@@ -30,6 +30,7 @@
     "forced_eos_token_id": null,
     "hidden_act": "gelu",
     "hidden_size": 1280,
+    "projection_dim": 1280,
     "id2label": {
       "0": "LABEL_0",
       "1": "LABEL_1"