Update build.sh to create swift xcframework

.gitignore

@@ -2,7 +2,10 @@ target
 build
 Cargo.lock
 /bindings/bdk-kotlin/local.properties
-/bindings/bdk-swift
+/bindings/bdk-swift/*
+!bindings/bdk-swift/bdkFFI-umbrella.h
+!bindings/bdk-swift/Info.plist
+!bindings/bdk-swift/module.modulemap
 /bindings/bdk-swift.swiftdoc
 /bindings/bdk-swift.swiftsourceinfo
 .gradle
@@ -17,3 +20,5 @@ testdb
 xcuserdata
 .lsp
 .clj-kondo
+*.xcframework
+*.xcframework.zip