Replace bytes.removesuffix() call

Replaces the bytes.removesuffix() call in fixup_pdf_template.py used to
remove Windows line endings with simply stripping the last 2 bytes of
the line. Note that fixup_pdf_template.py already checks that the last 2
bytes are "\r\n" before doing this.

bytes.removesuffix() is new to Python 3.9, while depot_tools currently
ships with only Python 3.8.

Change-Id: I1e49e0918154ddc0450d4ec05a08d29084ec8671
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/111190
Auto-Submit: K. Moon <kmoon@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/testing/tools/fixup_pdf_template.py b/testing/tools/fixup_pdf_template.py
index da2d608..1d38117 100755
--- a/testing/tools/fixup_pdf_template.py
+++ b/testing/tools/fixup_pdf_template.py
@@ -182,7 +182,7 @@
           if override_line_endings:
             # Replace CRLF with LF line endings for .in files.
             if line.endswith(WINDOWS_LINE_ENDING):
-              line = line.removesuffix(WINDOWS_LINE_ENDING) + UNIX_LINE_ENDING
+              line = line[:-len(WINDOWS_LINE_ENDING)] + UNIX_LINE_ENDING
               end_of_file_line_ending = True
             else:
               end_of_file_line_ending = line.endswith(UNIX_LINE_ENDING)