Address doxygen warnings

[aphelionz]

This PR updates the Doxyfile to address the following warnings generated via running doxygen v1.9.7 on docs/doxygen/Doxyfile:

warning: Tag 'HTML_TIMESTAMP' at line 1381 of file 'Doxyfile' has become obsolete.
         To avoid this warning please remove this line from your configuration file or upgrade it using "doxygen -u"
warning: Tag 'LATEX_TIMESTAMP' at line 2049 of file 'Doxyfile' has become obsolete.
         To avoid this warning please remove this line from your configuration file or upgrade it using "doxygen -u"
warning: Inheritance graph for 'Component' not generated, too many nodes (65), threshold is 50. Consider increasing DOT_GRAPH_MAX_NODES.
warning: Inheritance graph for 'DummyCriticalSection' not generated, too many nodes (162), threshold is 50. Consider increasing DOT_GRAPH_MAX_NODES.

Note that I did not address this warning but I'm happy to include the necessary changes here as well, if somebody can point out what exactly do do in the header file:

/Users/mark/Applications/JUCE/docs/doxygen/build/juce_audio_processors/format_types/juce_LV2Resources.h:10239: warning: end of file while inside a group

[tpoole]

Thank you for submitting this PR, but this work has already been done on our develop branch: ff835be