Update to swift-collections 1.1.1 on release/6.0, main, rebranch and next

[lorentey]

I skipped doing this in February, but toolchain builds should use the latest public package release.

[lorentey]

@swift-ci test

[lorentey]

@swift-ci build toolchain

[lorentey]

Well, that's unfortunate:

CMake Error at Sources/OrderedCollections/CMakeLists.txt:10 (add_library):
  Cannot find source file:

    Utilities/_UnsafeBitSet.swift

  Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm .h
  .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90 .f95 .f03 .hip .ispc


CMake Error at Sources/OrderedCollections/CMakeLists.txt:10 (add_library):
  No SOURCES given to target: OrderedCollections

[finagolfin]

CMake too old? @etcwilde plans to bump it to 3.26 or above later this year.

[etcwilde]

The capitalization of Utilities/_UnsafeBitSet.swift is wrong in the CMakeLists file. The filename is _UnsafeBitset.swift with a lowercase s.

[lorentey]

Yep; this is unfortunate as it will need to be corrected in a new swift-collections tag.

[lorentey]

@swift-ci test

[lorentey]

@swift-ci build toolchain

[lorentey]

Reverted this to a draft PR to avoid accidentally landing a branch spec here. (We are waiting for swift-collections 1.1.1 to ship.)

[lorentey]

Swift Collections 1.1.1 is out; this is ready to land.

[lorentey]

@swift-ci test

[lorentey]

@swift-ci build toolchain