tools/sizes.py: Restore to the prior behavior regarding output destination

once `tools/sizes.py` outputted to `stderr` rather `stdout` before da4a19f

(Arduino IDE 1.8.19 for Windows doesn't capture `stdout`, 2.0.0-rc6 does)

Author: jjsuwa-sys3175

tools/sizes.py

@@ -20,7 +20,7 @@
 import argparse
 import os
 import subprocess
-
+import sys
 
 def get_segment_sizes(elf, path, mmu):
     iram_size = 0
@@ -158,14 +158,14 @@ def main():
     for group, (segments, total) in sizes:
         number, used, segments = filter_segments(segments)
 
-        print(f". {group:<8}, used {used} / {total} bytes ({percentage(used, total)})")
-        print("|   SEGMENT  BYTES    DESCRIPTION")
+        sys.stderr.write(f". {group:<8}, used {used} / {total} bytes ({percentage(used, total)})\n")
+        sys.stderr.write("|   SEGMENT  BYTES    DESCRIPTION\n")
         for n, segment, size in segments:
             try:
-                print(f"{prefix(n, number)} ", end="")
+                sys.stderr.write(f"{prefix(n, number)} ")
             except UnicodeEncodeError:
-                print(f"{safe_prefix(n, number)} ", end="")
-            print(f"{segment:<8} {size:<8} {HINTS[segment]:<16}")
+                sys.stderr.write(f"{safe_prefix(n, number)} ")
+            sys.stderr.write(f"{segment:<8} {size:<8} {HINTS[segment]:<16}\n")
 
 
 if __name__ == "__main__":