Coverage upload does not work in CI

[mraspaud]

The coverage reported atm is 0%.

Sample output of the github actions run:

Run pytest --cov=pytroll-monitor pytroll_monitor/tests --cov-report=xml
============================= test session starts ==============================
platform linux -- Python 3.10.5, pytest-7.1.2, pluggy-1.0.0
rootdir: /home/runner/work/pytroll-monitor/pytroll-monitor
plugins: cov-3.0.0, requests-mock-1.9.3
collected 4 items
pytroll_monitor/tests/test_loggers.py .                                  [ 25%]
/usr/share/miniconda3/envs/test-environment/lib/python3.10/site-packages/coverage/inorout.py:519: CoverageWarning: Module pytroll-monitor was never imported. (module-not-imported)
  self.warn(f"Module {pkg} was never imported.", slug="module-not-imported")
/usr/share/miniconda3/envs/test-environment/lib/python3.10/site-packages/coverage/control.py:794: CoverageWarning: No data was collected. (no-data-collected)
  self._warn("No data was collected.", slug="no-data-collected")
/usr/share/miniconda3/envs/test-environment/lib/python3.10/site-packages/pytest_cov/plugin.py:308: CovReportWarning: Failed to generate report: No data to report.
  warnings.warn(CovReportWarning(message))
pytroll_monitor/tests/test_op5.py ...                                    [100%]WARNING: Failed to generate report: No data to report.
---------- coverage: platform linux, python 3.10.5-final-0 -----------
============================== 4 passed in 0.13s ===============================
0s
Run codecov/codecov-action@v1
/usr/bin/bash codecov.sh -n  -F unittests -Q github-action-v1.5.2 -e OS,PYTHON_VERSION,UNSTABLE -f ./coverage.xml
  _____          _
 / ____|        | |
| |     ___   __| | ___  ___ _____   __
| |    / _ \ / _` |/ _ \/ __/ _ \ \ / /
| |___| (_) | (_| |  __/ (_| (_) \ V /
 \_____\___/ \__,_|\___|\___\___/ \_/
                              Bash-1.0.3
==> git version 2.37.0 found
==> curl 7.68.0 (x86_64-pc-linux-gnu) libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3
Release-Date: 2020-01-08
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps telnet tftp 
Features: AsynchDNS brotli GSS-API HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP UnixSockets
==> GitHub Actions detected.
    Env vars used:
      -> GITHUB_ACTIONS:    true
      -> GITHUB_HEAD_REF:   
      -> GITHUB_REF:        refs/tags/v0.2.0
      -> GITHUB_REPOSITORY: pytroll/pytroll-monitor
      -> GITHUB_RUN_ID:     2688943750
      -> GITHUB_SHA:        b38bb147407c873b7223f036f3c0ac34dee7ac74
      -> GITHUB_WORKFLOW:   CI
project root: .
Yaml not found, that's ok! Learn more athttp://docs.codecov.io/docs/codecov-yaml
-> Found 1 reports
==> Detecting git/mercurial file structure
==> Appending build variables
+ OS
+ PYTHON_VERSION
+ UNSTABLE
==> Reading reports
- file not found at ./coverage.xml
--> No coverage data found.
    Please visit http://docs.codecov.io/docs/supported-languages
    search for your projects language to learn how to collect reports.