make examples-run fails with missing tlm-bridges/umi.h

[docrowd]

@ 42aa8ed7 , following the Quickstart instructions in README.md after successfully cloning submodules:

cd tests/
make examples-run

gives:

make[2]: Entering directory '/home/user/libsystemctlm-soc/tests/example-rtl-umi/obj_dir'
g++  -I.  -MMD -I/usr/share/verilator/include -I/usr/share/verilator/include/vltstd -DVM_COVERAGE=0 -DVM_SC=1 -DVM_TRACE=1 -DVM_TRACE_FST=0 -DVM_TRACE_VCD=1 -faligned-new -fcf-protection=none -Wno-bool-operation -Wno-sign-compare -Wno-uninitialized -Wno-unused-but-set-variable -Wno-unused-parameter -Wno-unused-variable -Wno-shadow     -I /home/user/systemc-2.3.4/include/ -I ../../../ -I ../../ -I .     -Os -c -o example-rtl-umi.o ../example-rtl-umi.cc
In file included from ../example-rtl-umi.cc:24:
../../../tlm-bridges/tlm2umi-bridge.h:15:10: fatal error: tlm-bridges/umi.h: No such file or directory
   15 | #include "tlm-bridges/umi.h"
      |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.

I'm not sure where umi.h should come from.