fix: update multibuild

Build broke, updating the multibuild version appears to fix it.

Author: hredestig

.travis.yml

@@ -68,7 +68,7 @@ matrix:
 
 before_install:
   - if [[ -n "${MB_PYTHON_VERSION}" ]]; then
-      (travis_retry git clone https://github.com/matthew-brett/multibuild.git && cd multibuild && git checkout edf5b691d0d565b4e65e655b983c11c883acbeca);
+      (travis_retry git clone https://github.com/matthew-brett/multibuild.git && cd multibuild && git checkout 37040e31b1044468027bd86991c805006a92bf09);
       TEST_DEPENDS="swiglpk optlang sympy decorator cython codecov coverage numpy scipy jsonschema six pytest pytest-cov pytest-benchmark tabulate";
       BUILD_DEPENDS="swiglpk optlang sympy cython numpy scipy";
       source multibuild/common_utils.sh;