bazel: update virtualenv to 20.28.1

ref: https://pypi.org/project/virtualenv/

bazel/notebook_requirements.in

@@ -9,7 +9,7 @@ scipy==1.14.1
 # OR-Tools build dependencies
 mypy==1.6.1
 mypy-protobuf==3.5.0
-virtualenv==20.24.6
+virtualenv==20.28.1
 black==24.8.0
 
 # Example dependencies

bazel/notebook_requirements.txt

@@ -333,7 +333,7 @@ uri-template==1.3.0
     # via jsonschema
 urllib3==2.2.2
     # via requests
-virtualenv==20.24.6
+virtualenv==20.28.1
     # via -r bazel/notebook_requirements.in
 wcwidth==0.2.6
     # via prompt-toolkit

bazel/ortools_requirements.in

@@ -9,7 +9,7 @@ scipy==1.14.1
 # OR-Tools build dependencies
 mypy==1.6.1
 mypy-protobuf==3.5.0
-virtualenv==20.24.6
+virtualenv==20.28.1
 black==24.8.0
 
 # Example dependencies

bazel/ortools_requirements.txt

@@ -69,5 +69,5 @@ tzdata==2023.3
     # via pandas
 urllib3==2.2.2
     # via requests
-virtualenv==20.24.6
+virtualenv==20.28.1
     # via -r bazel/ortools_requirements.in