While I appreciate the solutions of Martin and Milosz, my advice is: Don't do it. Your bibliography is basically formatted as a normal section (save the numbering), and footnotes should always be placed at the bottom of a page, even when they are part of section "X" and a new section "X+1" starts in the middle of the page. (Milosz: Your screenshot shows footnote no. 4 -- I wonder what the pages with footnotes no. 1--3 look like.) If you really abhor footnotes after section-bibliographies, consider switching to endnotes for the whole document (these notes may be placed in a separate section before the bibliography).
If you insist on positioning a footnote in the middle of a page and use a minipage environment for the text on the last page to do so, pay attention to the formatting of any "paragraph" that spans both the penultimate and the last page -- e.g., make sure that the last line on the penultimate page is justified.