Use python3_executable in presubmit scripts.

Bug: pdfium:1674
Change-Id: I5f7ea9faa96cb3b4c5b3974c73571b980dd5176d
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/95250
Reviewed-by: Nigi <nigi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/PRESUBMIT.py b/fpdfsdk/PRESUBMIT.py
index 50ec3a5..00c04ce 100644
--- a/fpdfsdk/PRESUBMIT.py
+++ b/fpdfsdk/PRESUBMIT.py
@@ -24,7 +24,7 @@
   src_path = input_api.os_path.dirname(input_api.PresubmitLocalPath())
   check_script = input_api.os_path.join(
       src_path, 'testing' , 'tools' , 'api_check.py')
-  cmd = [input_api.python_executable, check_script]
+  cmd = [input_api.python3_executable, check_script]
   try:
     input_api.subprocess.check_output(cmd)
     return []
diff --git a/public/PRESUBMIT.py b/public/PRESUBMIT.py
index a92463e..706999d 100644
--- a/public/PRESUBMIT.py
+++ b/public/PRESUBMIT.py
@@ -16,7 +16,7 @@
   src_path = input_api.os_path.dirname(input_api.PresubmitLocalPath())
   check_script = input_api.os_path.join(
       src_path, 'testing' , 'tools' , 'api_check.py')
-  cmd = [input_api.python_executable, check_script]
+  cmd = [input_api.python3_executable, check_script]
   try:
     input_api.subprocess.check_output(cmd)
     return []