"\r?" regex doesn't seem to work properly

Description

Regex("\r?\n") and other variants don't match "\r\n":

    print(try #/\r?\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"

See more "not matching" variants, and some related "matching" ones, in the reproduction section below.

Reproduction

        print(try #/\r?\n/#.firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try #/\r?\n/#.firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try #/(\r)?\n/#.firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try #/\r{0,1}\n/#.firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try #/(\r){0,1}\n/#.firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try #/\r?\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"
        print(try #/(\r)?\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"
        print(try #/\r{0,1}\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"
        print(try #/(\r){0,1}\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"
        print(try #/\r\n/#.firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try Regex("\r?\n").firstMatch(in: "\n") == nil ? "not matched" : "matched")  // prints "matched"
        print(try Regex("\r?\n").firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "not matched"
        print(try Regex("\r\n").firstMatch(in: "\r\n") == nil ? "not matched" : "matched")  // prints "matched"

Expected behavior

I expect all the "not matched" lines above to print "matched"

Environment

swift-driver version: 1.87.3 Apple Swift version 5.9.2 (swiftlang-5.9.2.2.56 clang-1500.1.0.2.5)
Target: arm64-apple-macosx14.0

Additional information

Xcode 15.2 (15C500b)
macOS Sonoma 14.2.1
Mac mini M2 2023

Start with the reproduction cases in the issue, comparing regex literals and Regex string patterns against "\r\n". Trace the matching behavior for optional carriage returns and verify the fix by making all listed "not matched" cases report a match while preserving the existing matching cases.