Update to Swift 5.9

Author: cpisciotta

.github/workflows/release.yml

@@ -5,7 +5,7 @@ on:
 name: Release
 
 env:
-  SWIFT_VERSION: 5.7
+  SWIFT_VERSION: 5.9
 
 jobs:
   create_release:

.github/workflows/xcbeautify.yml

@@ -8,7 +8,7 @@ on:
   merge_group: {}
 
 env:
-  SWIFT_VERSION: 5.7
+  SWIFT_VERSION: 5.9
 
 jobs:
   macos:

.swift-version

@@ -1 +1 @@
-5.7.1
+5.9

Makefile

@@ -58,7 +58,7 @@ package-linux-x86_64:
 	$(eval SWIFT_BUILD_FLAGS := $(SHARED_SWIFT_BUILD_FLAGS) --triple $(TARGET_TRIPLE))
 	$(eval BUILD_DIRECTORY := $(shell swift build --show-bin-path $(SWIFT_BUILD_FLAGS)))
 	docker run --rm --volume `pwd`:/workdir --workdir /workdir \
-		swift:5.7-bionic swift build $(SWIFT_BUILD_FLAGS)
+		swift:5.9 swift build $(SWIFT_BUILD_FLAGS)
 	tar --directory "$(BUILD_DIRECTORY)" --create --xz --file \
 		"$(PRODUCT_NAME).tar.xz" "$(PRODUCT_NAME)"
 

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.7
+// swift-tools-version:5.9
 import PackageDescription
 
 let package = Package(

README.md

@@ -59,7 +59,7 @@ In that directory, create a `Package.swift` file with the following contents.
 In addition, add an empty file named `Empty.swift` to the same location.
 
 ```swift
-// swift-tools-version: 5.6
+// swift-tools-version: 5.9
 import PackageDescription
 
 let package = Package(