🧹 Remove workaround for fixed np.str problem in Calamari

Older Calamari version had used deprecated np.str, remove the workaround
for this and require Calamari >= 1.0.6 instead.

See #87.

requirements.txt

@@ -1,7 +1,7 @@
 tensorflow >= 2.5.0
-numpy < 1.24.0  # XXX https://github.com/OCR-D/ocrd_calamari/issues/87
+numpy
 protobuf < 4.0  # XXX https://github.com/OCR-D/ocrd_calamari/issues/89
-calamari-ocr == 1.0.*
+calamari-ocr == 1.0.*, >= 1.0.6
 setuptools >= 41.0.0  # tensorboard depends on this, but why do we get an error at runtime?
 click
 ocrd >= 2.22.0