fix(liveness): misc minor changes (#135)

Author: atierian

AmplifyPlugins/Predictions/AWSPredictionsPlugin/Signing/SigV4Signer.swift

@@ -165,7 +165,7 @@ struct SigV4Signer {
     /// - Returns: A SigV4 Signed URL
     func sign(
         url: URL,
-        method: HTTPMethod,
+        method: HTTPMethod = .get,
         body: RequestBody? = nil,
         headers: [String: String] = [:],
         date: () -> Date = { .init() },
@@ -232,7 +232,7 @@ struct SigV4Signer {
         _storage.previousSignature = signature
 
         let queryString = canonicalQueryString + "&X-Amz-Signature=\(signature)"
-        let signedURL = url.appending(queryString: queryString)
+        let signedURL = url.replacing(queryString: queryString)
 
         return signedURL
     }

AmplifyPlugins/Predictions/AWSPredictionsPlugin/Signing/URL+Signing.swift

@@ -28,14 +28,13 @@ extension URL {
         return value
     }
 
-    func appending(queryString: String) -> URL {
+    func replacing(queryString: String) -> URL {
         let split = absoluteString.split(separator: "?")
         let url: URL?
         if split.count == 2 {
             let baseURL = String(split[0])
-            let existingQueryString = String(split[1])
             url = URL(
-                string: baseURL + "?" + existingQueryString + "&" + queryString
+                string: baseURL + "?" + queryString
             )
         } else {
             url = URL(string: absoluteString + "?" + queryString)