/usr/include/grantlee/ is in libgrantlee5-dev 5.1.0-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/grantlee/abstractlocalizer.h
/usr/include/grantlee/abstractmarkupbuilder.h
/usr/include/grantlee/bbcodebuilder.h
/usr/include/grantlee/cachingloaderdecorator.h
/usr/include/grantlee/context.h
/usr/include/grantlee/engine.h
/usr/include/grantlee/exception.h
/usr/include/grantlee/filter.h
/usr/include/grantlee/filterexpression.h
/usr/include/grantlee/grantlee_templates_export.h
/usr/include/grantlee/grantlee_textdocument_export.h
/usr/include/grantlee/grantlee_version.h
/usr/include/grantlee/markupdirector.h
/usr/include/grantlee/mediawikimarkupbuilder.h
/usr/include/grantlee/metatype.h
/usr/include/grantlee/node.h
/usr/include/grantlee/outputstream.h
/usr/include/grantlee/parser.h
/usr/include/grantlee/plaintextmarkupbuilder.h
/usr/include/grantlee/qtlocalizer.h
/usr/include/grantlee/rendercontext.h
/usr/include/grantlee/safestring.h
/usr/include/grantlee/taglibraryinterface.h
/usr/include/grantlee/template.h
/usr/include/grantlee/templateloader.h
/usr/include/grantlee/texthtmlbuilder.h
/usr/include/grantlee/token.h
/usr/include/grantlee/typeaccessor.h
/usr/include/grantlee/util.h
/usr/include/grantlee/variable.h