Bug#989783: libscotchmetis-dev: use METIS version 5

[Drew Parsons]

Package: libscotchmetis-dev
Version: 6.1.0-2
Severity: normal

By default Scotch builds Metis compatibility using Metis version 3.

Metis itself has been v5 for some time now. I think we should update
Scotch's Metis compatibility level to match.

Set 
 -DSCOTCH_METIS_VERSION=5
in Makefile.inc


-- System Information:
Debian Release: 11.0
  APT prefers testing-security
  APT policy: (500, 'testing-security'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-7-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_OOT_MODULE
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libscotchmetis-dev depends on:
ii  libscotch-dev  6.1.0-2

libscotchmetis-dev recommends no packages.

libscotchmetis-dev suggests no packages.