Remove unused exception parameter from pytorch/text/examples/libtorchtext/tokenizer/main.cpp

Summary:
`-Wunused-exception-parameter` has identified an unused exception parameter. This diff removes it.

This:
```
try {
    ...
} catch (exception& e) {
    // no use of e
}
```
should instead be written as
```
} catch (exception&) {
```

If the code compiles, this is safe to land.

Reviewed By: dmm-fb

Differential Revision: D58830948

fbshipit-source-id: 129097585ca4b0ae2ef3ef1621c290ea52375282

Author: David Tolnay

examples/libtorchtext/tokenizer/main.cpp

@@ -11,7 +11,7 @@ int main(int argc, const char* argv[]) {
   torch::jit::script::Module module;
   try {
     module = torch::jit::load(argv[1]);
-  } catch (const c10::Error& e) {
+  } catch (const c10::Error&) {
     return -1;
   }