Configure cppcheck's suppressions list.

.cppcheck

@@ -0,0 +1,3 @@
+returnByReference:Chaos/Hash/Md4.hpp:141
+returnByReference:Chaos/Hash/Md5.hpp:165
+returnByReference:Chaos/Hash/Sha1.hpp:134

.gitea/workflows/ChaosCi.yaml

@@ -86,6 +86,7 @@ jobs:
                    --enable=warning,performance,portability \
                    --suppress='*:*/_deps/*' \
                    --suppress=missingIncludeSystem \
+                   --suppressions-list=.cppcheck \
                    --inline-suppr \
                    --error-exitcode=1