add include guard to `resources.h` (#31) #700

Job	Run time
Windows Build (64 bit / x86_64)	6m 33s
Linux Build (64 bit / x86_64)	2m 37s
MacOS Build (x86_64)	5m 17s
MacOS Build (arm64)	5m 55s
Linux Installer (${{ matrix.bits }} bit / ${{ matrix.arch }})	0s
Linux Tests (${{ matrix.bits }} bit / ${{ matrix.arch }})	0s
MacOS Installer (${{ matrix.arch }})	0s
MacOS Tests (${{ matrix.arch }})	0s
Windows Tests (64 bit / x86_64)	0s
Windows Installer (64 bit / x86_64)	0s
Publish Catch2 Test Results	11s
	20m 33s

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