add main name to import function

[bravecorvus]

Description of changes:
I just made the changes to main_test.go which follow the docs. without the rename of main for the "package" github.com/aws-samples/lambda-go-samples , main_test.go will not be able to find the package namespace main.

However, this still does not fix the problem that since main.go is not actually a package (it is a program driver). I am not entirely sure how to test a main program in this way in idiomatic go, but I hope this gets a little closer to the fix.

The exact message in my code is:

main_test.go|6 col 2 error| import "github.com/aws-samples/lambda-go-samples" is a program, not an importable package

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[nmccready]

Why is this not merged?