vpython3: Fix path to python 3

Bug: 1036606
Change-Id: I035250757e346f89390b36d44701f0b6b8d8d024
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1995888
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>

vpython3

@@ -47,7 +47,7 @@ if [[ $MINGW != 0 && $DEPOT_TOOLS_BOOTSTRAP_PYTHON3 != 0 ]]; then
     bootstrap_python3
   fi
   PYTHON3_BIN_RELDIR="$base_dir/$(cat $base_dir/python3_bin_reldir.txt | xargs echo)"
-  exec "$base_dir/.cipd_bin/vpython3" -vpython-interpreter  "$PYTHON3_BIN_RELDIR/bin/python3" "$@"
+  exec "$base_dir/.cipd_bin/vpython3" -vpython-interpreter  "$PYTHON3_BIN_RELDIR/python3" "$@"
 else
   exec "$base_dir/.cipd_bin/vpython3" "$@"
 fi