avoid libffi broken default make target

* something's changed in the latest manylinux containers that broke the default `make` target for libffi- `make install` seems to work fine.

.github/workflows/ci.yaml

@@ -277,7 +277,6 @@ jobs:
           ((command -v apk && apk add libtool) || true) && \
           ./autogen.sh && \
           ./configure --without-gcc-arch --disable-docs --with-pic --enable-shared=no && \
-          make && \
           make install
         CIBW_ENVIRONMENT_PASS_LINUX: CFLAGS  # ensure that the build container can see our overridden build config
         CIBW_MANYLINUX_X86_64_IMAGE: ${{ matrix.manylinux_img || '' }}