Update TF version constraint to <2.6 (#4154)

* Update RELEASE.md

* Update version.py

* Update version.py

* Update version.py

* Update dependencies.py

* Update RELEASE.md

Author: dhruvesh09

RELEASE.md

@@ -33,6 +33,7 @@
 *   Depends on `kfp-pipeline-spec>=0.1.8,<0.2`.
 *   Depends on `ml-metadata>=1.2.0,<1.3.0`.
 *   Depends on `struct2tensor>=0.33.0,<0.34.0`.
+*   Depends on `tensorflow>=1.15.2,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,<2.6`.
 *   Depends on `tensorflow-data-validation>=1.2.0,<1.3.0`.
 *   Depends on `tensorflow-model-analysis>=0.33.0,<0.34.0`.
 *   Depends on `tensorflow-transform>=1.2.0,<1.3.0`.

tfx/dependencies.py

@@ -89,7 +89,7 @@ def make_required_install_packages():
       'numpy>=1.16,<1.20',
       'pyarrow>=1,<3',
       'pyyaml>=3.12,<6',
-      'tensorflow>=1.15.2,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,<3',
+      'tensorflow>=1.15.2,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,<2.6',
       'tensorflow-hub>=0.9.0,<0.13',
       'tensorflow-data-validation' + select_constraint(
           default='>=1.2.0,<1.3.0',