[deps] Bump djangosaml2 from 1.11.1 to 1.12.0

Bumps [djangosaml2](https://github.com/IdentityPython/djangosaml2) from 1.11.1 to 1.12.0.
- [Release notes](https://github.com/IdentityPython/djangosaml2/releases)
- [Changelog](https://github.com/IdentityPython/djangosaml2/blob/master/CHANGES)
- [Commits](IdentityPython/djangosaml2@v1.11.1...v1.12.0)

---
updated-dependencies:
- dependency-name: djangosaml2
  dependency-version: 1.12.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Federico Capoano <f.capoano@openwisp.io>

Author: dependabot[bot]

setup.py

@@ -62,7 +62,7 @@
         "Exscript~=2.6.28",
     ],
     extras_require={
-        "saml": ["djangosaml2==1.11.1"],
+        "saml": ["djangosaml2>=1.12.0,<1.13.0"],
         "openvpn_status": ["openvpn-status~=0.2.1"],
     },
     classifiers=[