Catching polymorphic exception by value

## Bug Report

### Incorrect Functionality

```
/opt/OpenTimelineIO/source/src/opentime/rationalTime.cpp: In static member function ‘static opentime::v1_0::RationalTime opentime::v1_0::RationalTime::from_timecode(const string&, double, opentime::v1_0::ErrorStatus*)’:
/opt/OpenTimelineIO/source/src/opentime/rationalTime.cpp:110:28: warning: catching polymorphic type ‘class std::exception’ by value [-Wcatch-value=]
110 | } catch(std::exception e) {
| ^
```
```
/opt/OpenTimelineIO/source/src/opentime/rationalTime.cpp: In static member function ‘static opentime::v1_0::RationalTime opentime::v1_0::RationalTime::from_time_string(const string&, double, opentime::v1_0::ErrorStatus*)’:
/opt/OpenTimelineIO/source/src/opentime/rationalTime.cpp:178:28: warning: catching polymorphic type ‘class std::exception’ by value [-Wcatch-value=]
178 | } catch(std::exception e) {
|
```

Read src/opentime/rationalTime.cpp around lines 110 and 178, where the warnings identify the exception handlers in from_timecode and from_time_string. Build the project and check that these compiler warnings are gone.

Written by the indexing model from the issue text.