Fix recent pandoc latex tables (jupyter#1536, jupyter#1566)

Pandoc >= 2.11.1 requires the calc package, and pandoc >= 2.11.3
requires the array package, for larger tables (taken from git blame
for pandoc's templates).  This commits adds the two packages in
an order similar to that in pandoc's templates.

share/jupyter/nbconvert/templates/latex/base.tex.j2

@@ -77,6 +77,8 @@ override this.-=))
     \usepackage{titling}
     \usepackage{longtable} % longtable support required by pandoc >1.10
     \usepackage{booktabs}  % table support for pandoc > 1.12.2
+    \usepackage{array}     % table support for pandoc >= 2.11.3
+    \usepackage{calc}      % table minipage width calculation for pandoc >= 2.11.1
     \usepackage[inline]{enumitem} % IRkernel/repr support (it uses the enumerate* environment)
     \usepackage[normalem]{ulem} % ulem is needed to support strikethroughs (\sout)
                                 % normalem makes italics be italics, not underlines