Remove unused exception parameter from fbandroid/native/lionhead/harn…

…esses/redex/RedexProguardParserFuzzer.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: D60515234

fbshipit-source-id: 37a9c18384233eb9fcfe233545166d2c86634f7c

source/model-generator/ModelTemplates.cpp

@@ -25,7 +25,7 @@ std::optional<ParameterPosition> TemplateVariableMapping::at(
     const std::string& name) const {
   try {
     return map_.at(name);
-  } catch (const std::out_of_range& exception) {
+  } catch (const std::out_of_range&) {
     return std::nullopt;
   }
 }