Remove unused print header in test

[maikel]

Relates to #98

[ClausKlein]

You are too fast!
The exec-with-awaitable-senders is not build on CI?

At least, I can't find it?

[dietmarkuehl]

It is certainly in tests/beman/execution26/CMakeLists.txt.

[maikel]

You are too fast! The exec-with-awaitable-senders is not build on CI?

At least, I can't find it?

I can see it perfectly fine, here for example

compilation: https://github.com/bemanproject/execution26/pull/99/checks#step:5:200

[183/372] Building CXX object tests/beman/execution26/CMakeFiles/beman.execution26.exec-with-awaitable-senders.test.dir/exec-with-awaitable-senders.test.cpp.o

test run: https://github.com/bemanproject/execution26/pull/99/checks#step:5:480

     Start 44: beman.execution26.exec-with-awaitable-senders.test
44/84 Test #44: beman.execution26.exec-with-awaitable-senders.test ......   Passed    0.00 sec