configure.ac: disable pytz_deprecation_shim with --disable-r

The pytz_deprecation_shim package is a dependency only of tzlocal,
which is already disabled with --disable-r.

Author: orlitzky

configure.ac

@@ -515,7 +515,7 @@ AC_ARG_ENABLE([notebook],
 AC_ARG_ENABLE([r],
   AS_HELP_STRING([--disable-r],
                  [disable build of the R package and related packages]), [
-    for pkg in r rpy2 r_jupyter tzlocal; do
+    for pkg in r rpy2 r_jupyter tzlocal pytz_deprecation_shim; do
       AS_VAR_SET([SAGE_ENABLE_$pkg], [$enableval])
     done
   ])