In that case just remove the libopenblas0 dependency altogether (both Build-Depends: and Depends: for the binary package).
Actually looking more closely at the source, mplcursors doesn't even use
BLAS at all.
- Bug#1028097: mplcursors: remove Build-Depends: libopenblas0 (... Drew Parsons
- Bug#1028097: mplcursors: remove Build-Depends: libopenbl... Drew Parsons