Remove stale copr build tag

The copr repo nsoffer/ovirt-imageio-preview is not maintained for few
years and does not exist now.

If we want to link to copr report for builds it should be the official
oVirt copr repo.

Signed-off-by: Nir Soffer <nirsof@gmail.com>

Author: nirs

README.md

@@ -10,7 +10,6 @@ SPDX-License-Identifier: GPL-2.0-or-later
 [![Downloads per month](https://img.shields.io/pypi/dm/ovirt-imageio)](https://pypi.org/project/ovirt-imageio/)
 [![License](https://img.shields.io/github/license/oVirt/ovirt-imageio)](https://pypi.org/project/ovirt-imageio/)
 [![CI status](https://github.com/oVirt/ovirt-imageio/actions/workflows/ci.yml/badge.svg)](https://github.com/oVirt/ovirt-imageio/actions)
-[![Copr build status](https://copr.fedorainfracloud.org/coprs/nsoffer/ovirt-imageio-preview/package/ovirt-imageio/status_image/last_build.png)](https://copr.fedorainfracloud.org/coprs/nsoffer/ovirt-imageio-preview/package/ovirt-imageio/)
 
 ovirt-imageio enables uploading and downloading of disks and snapshots using HTTPS.