Have there been any experiments since then to make his observation obsolete?
"Spontaneous generation" as Pasteur defined it was known species (flies, mice, etc.) suddenly within a short time frame popping into existence on appropriate substrate. Some of Pasteur's original experimental apparatuses remain at the Pasteur Institute where they still have not spontaneously produced modern bacteria. I believe it is universally accepted that such a thing does not occur.
All of this says nothing about the possibility of abiogenesis as we would define it, being a completely different creature. Using Pasteur's experiments to forbid prebiotic evolution and abiogenesis would be like stubbornly continuing to be puzzled by the massive heat output of the sun--we now know that the heat is due to fusion, which no one before 1920 would have dreamed about.