This has usually been presented as something "said shortly before his death" without any definite source, but appears to be entirely spurious. The "FAQ about the life and thoughts of Albert Schweitzer" http://www.schweitzer.org/faq?lang=en#rasist asserts "This quote is utterly false and is an outrageously inaccurate picture of Dr. Schweitzer’s view of Africans. Dr. Schweitzer never said or wrote anything remotely like this. It does NOT appear in the book African Notebook." This refers to some citations of it being from Afrikanische Geschichten (1938), which was translated as From My African Notebook (1939) by Mrs. C. E. B Russell
Misattributed