Add a GeometryCollection convert method for GeoInterface (#207) #324

Job	Run time
Julia 1.9 - ubuntu-latest - x64 - push	5m 34s
Julia 1.9 - macOS-latest - x64 - push	7m 2s
Julia 1.9 - windows-latest - x64 - push	7m 57s
Julia 1 - ubuntu-latest - x64 - push	4m 59s
Julia 1 - macOS-latest - x64 - push	6m 47s
Julia 1 - windows-latest - x64 - push	7m 0s
Julia nightly - ubuntu-latest - x64 - push	9m 34s
Julia nightly - macOS-latest - x64 - push	10m 52s
Julia nightly - windows-latest - x64 - push	11m 55s
	1h 11m 40s

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