Update to 1.81.0 with backport for mpl

.gitmodules

@@ -34,9 +34,6 @@
 [submodule "Submodules/multi_index"]
 	path = Submodules/multi_index
 	url = https://github.com/boostorg/multi_index
-[submodule "Submodules/mpl"]
-	path = Submodules/mpl
-	url = https://github.com/boostorg/mpl
 [submodule "Submodules/move"]
 	path = Submodules/move
 	url = https://github.com/boostorg/move
@@ -103,3 +100,6 @@
 [submodule "Submodules/algorithm"]
 	path = Submodules/algorithm
 	url = https://github.com/boostorg/algorithm
+[submodule "Submodules/mpl"]
+	path = Submodules/mpl
+	url = https://github.com/21-DOT-DEV/mpl

Package.swift

@@ -4,9 +4,8 @@
 import PackageDescription
 
 let package = Package(
-    name: "Boost.swift",
+    name: "Boost",
     products: [
-        // Products define the executables and libraries a package produces, and make them visible to other packages.
         .library(name: "algorithm", targets: ["algorithm"]),
         .library(name: "array", targets: ["array"]),
         .library(name: "assert", targets: ["assert"]),
@@ -43,13 +42,7 @@ let package = Package(
         .library(name: "utility", targets: ["utility"]),
         .library(name: "variant", targets: ["variant"]),
     ],
-    dependencies: [
-        // Dependencies declare other packages that this package depends on.
-        // .package(url: /* package url */, from: "1.0.0"),
-    ],
     targets: [
-        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
-        // Targets can depend on other targets in this package, and on products in packages this package depends on.
         .target(name: "algorithm"),
         .target(name: "array"),
         .target(name: "assert"),