chore: update libK submodule to 87b4e6f5

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: yannrichet

tools/gitmodules-shas

@@ -1,5 +1,5 @@
 # This file records the specific commit SHAs for each submodule
 # It is automatically generated and should be updated when submodules are updated
 # Format: <submodule_path> <commit_sha>
-src/libK 790d56c2e4bc5acf83698cbfc3dd1a21bd339b14
+src/libK 87b4e6f5456d7b4f242e98b4c254e2a5c49fa61e
 src/slapack 72a7f3753e02b0471e93296f2b22877c6fee7328