THRIFT-4990 Upgrade to .NET Core 3.1 (LTS)
Client: netstd
Patch: Jens Geyer

This closes #1961
diff --git a/configure.ac b/configure.ac
index f11ab13..64283a8 100755
--- a/configure.ac
+++ b/configure.ac
@@ -505,7 +505,7 @@
 if test "$with_netstd" = "yes";  then
   AC_PATH_PROG([DOTNETCORE], [dotnet])
   if [[ -x "$DOTNETCORE" ]] ; then
-    AX_PROG_DOTNETCORE_VERSION( [3.0.0], have_netstd="yes", have_netstd="no")
+    AX_PROG_DOTNETCORE_VERSION( [3.1.0], have_netstd="yes", have_netstd="no")
   fi
 fi
 AM_CONDITIONAL(WITH_DOTNET, [test "$have_netstd" = "yes"])