ci: add MIRI_LEAK_CHECK=1 on ci

Author: driftluo

ci/miri.sh

@@ -19,6 +19,7 @@ case "${group}" in
             cargo miri test --all-features \
             -p crossbeam-channel 2>&1 | ts -i '%.s  '
         # -Zmiri-ignore-leaks is needed because we use detached threads in tests in tests/golang.rs: https://github.com/rust-lang/miri/issues/1371
+        MIRI_LEAK_CHECK='1' \
         MIRIFLAGS="${MIRIFLAGS} -Zmiri-ignore-leaks" \
             cargo miri test --all-features \
             -p crossbeam-channel --test golang 2>&1 | ts -i '%.s  '