Disable existential any build setting (#312)

Motivation:

On 5.8, if the experiment existential any setting is enabled and a
consuming package holds an existential of a type from swift-log without
an explicit 'any' then the build will fail.

Modifications:

- Disable the setting

Result:

Users of 5.8 aren't broken

Package.swift

@@ -15,10 +15,6 @@
 
 import PackageDescription
 
-let swiftSettings: [SwiftSetting] = [
-    .enableUpcomingFeature("ExistentialAny"),
-]
-
 let package = Package(
     name: "swift-log",
     products: [
@@ -27,13 +23,11 @@ let package = Package(
     targets: [
         .target(
             name: "Logging",
-            dependencies: [],
-            swiftSettings: swiftSettings
+            dependencies: []
         ),
         .testTarget(
             name: "LoggingTests",
-            dependencies: ["Logging"],
-            swiftSettings: swiftSettings
+            dependencies: ["Logging"]
         ),
     ]
 )

docker/docker-compose.2204.510.yaml

@@ -13,6 +13,8 @@ services:
     environment:
       - WARN_AS_ERROR_ARG=-Xswiftc -warnings-as-errors
       #- SANITIZER_ARG=--sanitize=thread
+      # Generated test manifest uses existentials without 'any'.
+      #- EXISTENTIAL_ANY_ARG=-Xswiftc -enable-upcoming-feature -Xswiftc ExistentialAny
 
   shell:
     image: swift-log:22.04-5.10

docker/docker-compose.2204.59.yaml

@@ -13,6 +13,7 @@ services:
     image: swift-log:22.04-5.9
     environment:
       - WARN_AS_ERROR_ARG=-Xswiftc -warnings-as-errors
+      - EXISTENTIAL_ANY_ARG=-Xswiftc -enable-upcoming-feature -Xswiftc ExistentialAny
       #- SANITIZER_ARG=--sanitize=thread
 
   shell:

docker/docker-compose.2204.main.yaml

@@ -16,6 +16,8 @@ services:
       - IMPORT_CHECK_ARG=--explicit-target-dependency-import-check error
       - EXPLICIT_SENDABLE_ARG=-Xswiftc -require-explicit-sendable
       - STRICT_CONCURRENCY_ARG=-Xswiftc -strict-concurrency=complete
+      # Generated test manifest uses existentials without 'any'.
+      #- EXISTENTIAL_ANY_ARG=-Xswiftc -enable-upcoming-feature -Xswiftc ExistentialAny
 
   shell:
     image: swift-log:22.04-main

docker/docker-compose.yaml

@@ -28,7 +28,7 @@ services:
 
   test:
     <<: *common
-    command: /bin/bash -xcl "swift test $${WARN_AS_ERROR_ARG-} $${SANITIZER_ARG-} $${IMPORT_CHECK_ARG-} $${EXPLICIT_SENDABLE_ARG-} $${STRICT_CONCURRENCY_ARG-}"
+    command: /bin/bash -xcl "swift test $${WARN_AS_ERROR_ARG-} $${SANITIZER_ARG-} $${IMPORT_CHECK_ARG-} $${EXPLICIT_SENDABLE_ARG-} $${STRICT_CONCURRENCY_ARG-} $${EXISTENTIAL_ANY_ARG-}"
 
   # util