save_output creates incomplete file names if source file name has more than one period

If a source file has multiple periods in the filename, calling `save_output` drops all parts of the filename after the first period

**To Reproduce**
Process a file named `sample.file.1.jpg`. Call `.save_output(path, output_format="csv")`. Results in `sample.csv` being produced.

**Expected behavior**
Calling `save_output` in the outlined scenario should produce `sample.file.1.csv`.