Add support for 'visibility' attribute preview for Repositories (#1872)

Expose the new 'visibility' attribute for repository objects.

Fixes #1446

github/Organization.py

@@ -463,6 +463,7 @@ class Organization(github.GithubObject.CompletableGithubObject):
         description=github.GithubObject.NotSet,
         homepage=github.GithubObject.NotSet,
         private=github.GithubObject.NotSet,
+        visibility=github.GithubObject.NotSet,
         has_issues=github.GithubObject.NotSet,
         has_wiki=github.GithubObject.NotSet,
         has_downloads=github.GithubObject.NotSet,
@@ -506,6 +507,9 @@ class Organization(github.GithubObject.CompletableGithubObject):
         assert private is github.GithubObject.NotSet or isinstance(
             private, bool
         ), private
+        assert visibility is github.GithubObject.NotSet or isinstance(
+            visibility, str
+        ), visibility
         assert has_issues is github.GithubObject.NotSet or isinstance(
             has_issues, bool
         ), has_issues
@@ -551,6 +555,8 @@ class Organization(github.GithubObject.CompletableGithubObject):
             post_parameters["homepage"] = homepage
         if private is not github.GithubObject.NotSet:
             post_parameters["private"] = private
+        if visibility is not github.GithubObject.NotSet:
+            post_parameters["visibility"] = visibility
         if has_issues is not github.GithubObject.NotSet:
             post_parameters["has_issues"] = has_issues
         if has_wiki is not github.GithubObject.NotSet:
@@ -576,7 +582,10 @@ class Organization(github.GithubObject.CompletableGithubObject):
         if delete_branch_on_merge is not github.GithubObject.NotSet:
             post_parameters["delete_branch_on_merge"] = delete_branch_on_merge
         headers, data = self._requester.requestJsonAndCheck(
-            "POST", f"{self.url}/repos", input=post_parameters
+            "POST",
+            f"{self.url}/repos",
+            input=post_parameters,
+            headers={"Accept": Consts.repoVisibilityPreview},
         )
         return github.Repository.Repository(
             self._requester, headers, data, completed=True
@@ -987,7 +996,9 @@ class Organization(github.GithubObject.CompletableGithubObject):
         """
         assert isinstance(name, str), name
         headers, data = self._requester.requestJsonAndCheck(
-            "GET", f"/repos/{self.login}/{name}"
+            "GET",
+            f"/repos/{self.login}/{name}",
+            headers={"Accept": Consts.repoVisibilityPreview},
         )
         return github.Repository.Repository(
             self._requester, headers, data, completed=True
@@ -1024,6 +1035,7 @@ class Organization(github.GithubObject.CompletableGithubObject):
             self._requester,
             f"{self.url}/repos",
             url_parameters,
+            headers={"Accept": Consts.repoVisibilityPreview},
         )
 
     def get_team(self, id):