Add nightly 5.7 CI (#1438)

.github/workflows/ci.yaml

@@ -24,6 +24,9 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - image: swiftlang/swift:nightly-5.7-focal
+            # No TSAN because of: https://github.com/apple/swift/issues/59068
+            # swift-test-flags: "--sanitize=thread"
           - image: swift:5.6-focal
             # No TSAN because of: https://github.com/apple/swift/issues/59068
             # swift-test-flags: "--sanitize=thread"
@@ -50,6 +53,16 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - image: swiftlang/swift:nightly-5.7-focal
+            env:
+              MAX_ALLOCS_ALLOWED_bidi_1k_rpcs_10_requests: 428000
+              MAX_ALLOCS_ALLOWED_bidi_1k_rpcs_1_request: 176000
+              MAX_ALLOCS_ALLOWED_embedded_server_bidi_1k_rpcs_10_small_requests: 110000
+              MAX_ALLOCS_ALLOWED_embedded_server_bidi_1k_rpcs_1_small_request: 65000
+              MAX_ALLOCS_ALLOWED_embedded_server_unary_1k_rpcs_1_small_request: 61000
+              MAX_ALLOCS_ALLOWED_unary_1k_ping_pong: 174000
+              MAX_ALLOCS_ALLOWED_unary_1k_ping_pong_interceptors_client: 181000
+              MAX_ALLOCS_ALLOWED_unary_1k_ping_pong_interceptors_server: 181000
           - image: swift:5.6-focal
             env:
               MAX_ALLOCS_ALLOWED_bidi_1k_rpcs_10_requests: 429000
@@ -95,6 +108,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - image: swiftlang/swift:nightly-5.7-focal
           - image: swift:5.6-focal
           - image: swift:5.5-focal
           - image: swift:5.4-focal