NEWS: Fix release date for 2.7.0 beta1
NEWS: Fix release date for 2.7.0 beta1

Commit b6ad806f used a wrong date.

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

yiannist/ganeti,dimara/ganeti,leshchevds/ganeti,andir/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,leshchevds/ganeti,andir/ganeti,bitemyapp/ganeti,mbakke/ganeti,andir/ganeti,bitemyapp/ganeti,dimara/ganeti,onponomarev/ganeti,mbakke/ganeti,ganeti/ganeti,grnet/snf-ganeti,ganeti/ganeti,yiannist/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,apyrgio/ganeti,mbakke/ganeti,leshchevds/ganeti,yiannist/ganeti,apyrgio/ganeti