libboost-thread-dev 1.71.0.0ubuntu2 (i386 binary) in ubuntu focal

 This package forms part of the Boost C++ Libraries collection.
 .
 Toolkit for writing C++ programs that execute as multiple,
 asynchronous, independent, threads-of-execution. Each thread has its
 own machine state including program instruction counter and
 registers.
 .
 This package is a dependency package, which depends on Debian's default
 Boost version (currently 1.71).