Changed expected version-number to "R".

[ Merge of http://go/wvgerrit/83184 ]

On master branch, `request_license_test` should be expecting the latest
android release version (now "R").

Test: Run `request_license_test` on Android R
Bug: 137784842
Change-Id: I09add2c2752b5af09bd2f27bd9f4ce7bc6fc07eb

libwvdrmengine/cdm/test/request_license_test.cpp

@@ -5551,7 +5551,7 @@ TEST(VersionNumberTest, VersionNumberChangeCanary) {
   std::string release_number =
       android::base::GetProperty("ro.build.version.release", "");
   ASSERT_TRUE(release_number.size() > 0);
-  EXPECT_STREQ("10", release_number.c_str())
+  EXPECT_STREQ("R", release_number.c_str())
       << "The Android version number has changed. You need to update this test "
          "and also possibly update the Widevine version number in "
          "properties_android.cpp.";