Disable warnings as errors on 6.0

Motivation:

We currently have a range of thread-safety warnings on Swift 6.0 (which
will be errors in Swift 6 Language mode). Resolving these is out of
scope for CI work.

Modifications:

Disabled warnings-as-errors on Swift 6 CI pipelines

Result:

Resolve Swift 6 CI failures.

.github/workflows/main.yml

@@ -14,6 +14,6 @@ jobs:
             linux_5_8_enabled: false
             linux_5_9_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
             linux_5_10_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
-            linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
             linux_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
             linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"

.github/workflows/pull_request.yml

@@ -16,7 +16,7 @@ jobs:
         with:
             linux_5_9_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
             linux_5_10_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error"
-            linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
             linux_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
             linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
 

.swift-format

@@ -18,6 +18,12 @@
   "maximumBlankLines" : 1,
   "respectsExistingLineBreaks" : true,
   "prioritizeKeepingFunctionOutputTogether" : true,
+  "noAssignmentInExpressions" : {
+    "allowedFunctions" : [
+      "XCTAssertNoThrow",
+      "XCTAssertThrowsError"
+    ]
+  },
   "rules" : {
     "AllPublicDeclarationsHaveDocumentation" : false,
     "AlwaysUseLiteralForEmptyCollectionInit" : false,