Update dependency grpc/grpc-swift to v1.26.1 (#789)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Bryce Buchanan <[email protected]>

Author: renovate[bot]

Package.swift

@@ -31,7 +31,7 @@ let package = Package(name: "opentelemetry-swift",
                       ],
                       dependencies: [
                         .package(url: "https://github.com/apple/swift-nio.git", from: "2.0.0"),
-                        .package(url: "https://github.com/grpc/grpc-swift.git", exact: "1.24.2"),
+                        .package(url: "https://github.com/grpc/grpc-swift.git", exact: "1.26.1"),
                         .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.30.0"),
                         .package(url: "https://github.com/apple/swift-log.git", from: "1.6.3"),
                         .package(url: "https://github.com/apple/swift-metrics.git", from: "2.7.0"),