In order to update catch2 the following changes were made:
- CMakeLists.txt: import catch2 with FetchContent_Declare, this will
  make it more flexible and easier to update
- removed main for tests, since it is not mandatory and it doesn't add
  any value of having it
- renaming includes in all the files

error: moving ‘a’ of type ‘arduino::String’ to itself [-Werror=self-move]
Which may happen if if GCC_VERSION is not defined, and instead __GNUC__
is defined

since for catch2 '[' is not a valid character in the tag name

Signed-off-by: iabdalkader <[email protected]>

Catch2 update

Add SPI bus mode support (controller/peripheral)

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Those who wish to make a monetary contribution can still do so by purchasing official Arduino products. For this reason,
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Remove donation links from readme