Merge pull request from GHSA-7cc2-r658-7xpf

This fixes a vulnerability with the `CODER_OIDC_EMAIL_DOMAIN` option,
where users with a superset of the allowed email domain would be allowed
to login. For example, given `CODER_OIDC_EMAIL_DOMAIN=google.com`, a
user would be permitted entry if their email domain was
`colin-google.com`.

coderd/userauth_test.go

@@ -798,6 +798,17 @@ func TestUserOIDC(t *testing.T) {
 			"kwc.io",
 		},
 		StatusCode: http.StatusOK,
+	}, {
+		Name: "EmailDomainSubset",
+		IDTokenClaims: jwt.MapClaims{
+			"email":          "colin@gmail.com",
+			"email_verified": true,
+		},
+		AllowSignups: true,
+		EmailDomain: []string{
+			"mail.com",
+		},
+		StatusCode: http.StatusForbidden,
 	}, {
 		Name:          "EmptyClaims",
 		IDTokenClaims: jwt.MapClaims{},