Workbench Fails if Temp File Already Exists
The logic below is a bit confusing. Recall that `input_csv` is a (at the moment, proposed) path of the data in a temp directory.  It seems to be working when a file at path `input_csv` does not already exist, but it will not work if, say, two consecutive runs of Workbench are completed back-to-back (in which case the OS doesn't necessarily delete the temp files). 

https://github.com/mjordan/islandora_workbench/blob/017d89434fcd5de8147a3b40668e555504720def/workbench_utils.py#L3597C1-L3604

We could instead change it to
```python
elif file_path.startswith('http') is True:
        input_csv_path = get_extracted_csv_file_path(config)
        if os.path.exists(input_csv_path):
            os.remove(input_csv_path)
        get_csv_from_google_sheet(config)
    elif file_path.endswith('.xlsx') is True:
        input_csv_path = get_extracted_csv_file_path(config)
        if os.path.exists(input_csv_path):
            os.remove(input_csv_path)
        get_csv_from_excel(config)
```
so that the code proceeds in both cases, but only after deleting the temp file if it already exists. 
diff --git a/workbench_utils.py b/workbench_utils.py
index 1f7bab9..e9a2aeb 100644
--- a/workbench_utils.py
+++ b/workbench_utils.py
@@ -3596,12 +3596,14 @@ def get_csv_data(config, csv_file_target='node_fields', file_path=None):
         input_csv_path = file_path
     elif file_path.startswith('http') is True:
         input_csv_path = get_extracted_csv_file_path(config)
-        if not os.path.exists(input_csv_path):
-            get_csv_from_google_sheet(config)
+        if os.path.exists(input_csv_path):
+            os.remove(input_csv_path)
+        get_csv_from_google_sheet(config)
     elif file_path.endswith('.xlsx') is True:
         input_csv_path = get_extracted_csv_file_path(config)
-        if not os.path.exists(input_csv_path):
-            get_csv_from_excel(config)
+        if os.path.exists(input_csv_path):
+            os.remove(input_csv_path)
+        get_csv_from_excel(config)
     else:
         input_csv_path = os.path.join(config['input_dir'], file_path)
 
['workbench_utils.py']