ci: Update meson requirement for DPDK 21.05.

A recent change [1] in DPDK bumped requirements on meson to 0.49.2.

1: https://git.dpdk.org/dpdk/commit/?id=8c1053083678

Signed-off-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

.ci/linux-prepare.sh

@@ -23,7 +23,7 @@ cd ..
 pip3 install --disable-pip-version-check --user \
     flake8 hacking sphinx pyOpenSSL wheel setuptools pyelftools
 pip3 install --user --upgrade docutils
-pip3 install --user  'meson==0.47.1'
+pip3 install --user  'meson==0.49.2'
 
 if [ "$M32" ]; then
     # Installing 32-bit libraries.