MAINT: Remove xlrd version limitation

setup.py

@@ -156,7 +156,7 @@ def setup_package():
         author_email='h.tomwoerden@indiscale.com',
         install_requires=["caosdb>=0.4.0",
                           "openpyxl>=3.0.0",
-                          "xlrd==1.2.0",
+                          "xlrd>=1.2.0",
                           ],
         packages=find_packages('src'),
         package_dir={'': 'src'},