chore: Fix compiler warnings (#809)

Author: jbelkins

Sources/SmithyHTTPAuth/SigV4Signer.swift

@@ -52,7 +52,7 @@ public class SigV4Signer: SmithyHTTPAuthAPI.Signer {
             )
         }
 
-        var signingConfig = try constructSigningConfig(identity: identity, signingProperties: signingProperties)
+        let signingConfig = try constructSigningConfig(identity: identity, signingProperties: signingProperties)
 
         let unsignedRequest = requestBuilder.build()
         let crtUnsignedRequest: HTTPRequestBase = isBidirectionalStreamingEnabled ?

Tests/SmithyRetriesTests/DefaultRetryStrategy/DefaultRetryStrategyTests.swift

@@ -28,7 +28,7 @@ final class DefaultRetryStrategyTests: XCTestCase {
 
     override func setUp() {
         backoffStrategy = .init()
-        backoffStrategy.random = { 1.0 }
+        backoffStrategy.random = { @Sendable () -> Double in 1.0 }
         options = RetryStrategyOptions(backoffStrategy: backoffStrategy, maxRetriesBase: 2)
         subject = DefaultRetryStrategy(options: options)
         mockSleeper = { self.actualDelay = $0 }

Tests/SmithyRetriesTests/DefaultRetryStrategy/ExponentialBackoffStrategyTests.swift

@@ -16,15 +16,15 @@ final class ExponentialBackoffStrategyTests: XCTestCase {
     override func setUp() {
         subject = ExponentialBackoffStrategy()
         // Randomization is disabled to allow easy, repeatable verification of basic behavior.
-        subject.random = { 1.0 }
+        subject.random = { @Sendable () -> Double in 1.0 }
     }
 
     func test_backoffStrategy_multipliesByBackoffFactor() {
-        subject.random = { 0.25 }
+        subject.random = { @Sendable () -> Double in 0.25 }
         XCTAssertEqual(subject.computeNextBackoffDelay(attempt: 0), 0.25)
-        subject.random = { 0.5 }
+        subject.random = { @Sendable () -> Double in 0.5 }
         XCTAssertEqual(subject.computeNextBackoffDelay(attempt: 0), 0.5)
-        subject.random = { 0.75 }
+        subject.random = { @Sendable () -> Double in 0.75 }
         XCTAssertEqual(subject.computeNextBackoffDelay(attempt: 0), 0.75)
     }