Update code coverage settings:

codecov.yml file - ignore dirs

close #2352

.codecov.yml

@@ -0,0 +1,25 @@
+# Copyright 2019 - 2021 Alexander Grund
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
+#
+# Sample codecov configuration file. Edit as required
+
+codecov:
+  max_report_age: off
+  require_ci_to_pass: yes
+  notify:
+    # Increase this if you have multiple coverage collection jobs
+    after_n_builds: 1
+    wait_for_ci: yes
+
+# Change how pull request comments look
+comment:
+  layout: "reach,diff,flags,files,footer"
+
+# Ignore specific files or folders. Glob patterns are supported.
+# See https://docs.codecov.com/docs/ignoring-paths
+ignore:
+  - extra/*
+  - extra/**/*
+  - test/*
+  - test/**/*

CHANGELOG.md

@@ -2,6 +2,7 @@ Version XXX:
 
 * Add individual tests to CMake workflow.
 * Update CI to include gcc 11, clang 12, msvc 14.3. 
+* Update code coverage settings.
 
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