[output] write download progress indicator to stderr

gallery_dl/output.py

@@ -296,10 +296,10 @@ class TerminalOutput(NullOutput):
         bdl = util.format_value(bytes_downloaded)
         bps = util.format_value(bytes_per_second)
         if bytes_total is None:
-            print("\r{:>7}B {:>7}B/s ".format(bdl, bps), end="")
+            sys.stderr.write("\r{:>7}B {:>7}B/s ".format(bdl, bps))
         else:
-            print("\r{:>3}% {:>7}B {:>7}B/s ".format(
-                bytes_downloaded * 100 // bytes_total, bdl, bps), end="")
+            sys.stderr.write("\r{:>3}% {:>7}B {:>7}B/s ".format(
+                bytes_downloaded * 100 // bytes_total, bdl, bps))
 
 
 class ColorOutput(TerminalOutput):

gallery_dl/version.py

@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
-__version__ = "1.19.3"
+__version__ = "1.20.0-dev"