Disable txfonts package in scribble/acmart

Commit c62d008cf include txfonts into the set of
default LaTeX packages. However, txfonts changes
the main font of the document, conflicting the
requirement of acmart articles.

We skip txfonts by setting packageTxfonts to nop.

scribble-lib/scribble/acmart/acmart-load.tex

@@ -5,6 +5,7 @@
 \renewcommand\packageTocstyle\relax
 \renewcommand\packageMathabx{\ifx\bigtimes\undefined \usepackage{mathabx} \else \relax \fi}
 % Both 'mathabx' and 'newtxmath' (required by the 'acmart' class) define a '\bigtimes' command. 
+\renewcommand\packageTxfonts\relax
 \let\Footnote\undefined
 \let\captionwidth\undefined
 \renewcommand{\renewrmdefault}{}