Set file mode in the argparse argument

Bug: webrtc:13607
Change-Id: I7943761933e0e110ff16b65284d8b36644b5c4ea
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251381
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Christoffer Jansson <jansson@google.com>
Cr-Commit-Position: refs/heads/main@{#35970}

tools_webrtc/perf/webrtc_dashboard_upload.py

@@ -58,7 +58,7 @@ def _CreateParser():
                       required=True,
                       help='Which dashboard to use.')
   parser.add_argument('--input-results-file',
-                      type=argparse.FileType(),
+                      type=argparse.FileType('rb'),
                       required=True,
                       help='A HistogramSet proto file with output from '
                       'WebRTC tests.')