update memoffset version

[trickster]

CC: rust-lang/rust#111839

[lnicola]

Can you also bump the version to 0.15.12?

[est31]

(coming from the rust-lang issue) @trickster did you run tests with --features memoffset/unstable_offset_of enabled? What is the output?

[trickster]

@est31

This is the output.

cargo +nightly test --features=memoffset/unstable_offset_of --all

running 3 tests
test green::tests::assert_send_sync ... ok
test green::tests::test_size_of ... ok
test syntax_text::tests::test_text_equality ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running tests/tidy.rs (/Users/siva/rust-target/debug/deps/tidy-071579816caf0f4a)

running 1 test
test check_code_formatting ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.81s

     Running unittests src/main.rs (/Users/siva/rust-target/debug/deps/xtask-f7dfc96464a1433a)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running tests/tidy.rs (/Users/siva/rust-target/debug/deps/tidy-a0b606e5416fb32e)

running 1 test
test test_formatting ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.42s

   Doc-tests rowan

running 1 test
test src/green/builder.rs - green::builder::GreenNodeBuilder<'_>::checkpoint (line 63) ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.42s

[est31]

@trickster thanks for verifying it works. I'll check the box in the issue.