Add fresh flag to suggested cmake commands for testing

[peverwhee]

Adds --fresh flag to example cmake commands; tests don't otherwise pick up changes without a clean build directory.

[climbfuji]

Should we also make this change in .github/{workflows,actions}/* ?

[peverwhee]

@DomHeinzeller good call - can't hurt. done!

[gold2718]

This looks good but the change should also be added to #691.

[climbfuji]

This looks good but the change should also be added to #691.

Shouldn't we just merge this and update #691 from develop?

[peverwhee]

@climbfuji I bet @gold2718 means that we should add the flag to the README in the new nested suites test (which doesn't exist on develop yet)

[climbfuji]

@climbfuji I bet @gold2718 means that we should add the flag to the README in the new nested suites test (which doesn't exist on develop yet)

Got it, thanks. I added it as a suggestion so that we can add it before merging and don't forget.

[mkavulich]

@climbfuji I bet @gold2718 means that we should add the flag to the README in the new nested suites test (which doesn't exist on develop yet)

Got it, thanks. I added it as a suggestion so that we can add it before merging and don't forget.

@climbfuji Does this mean this PR needs an update after the merge from develop?

[climbfuji]

@climbfuji I bet @gold2718 means that we should add the flag to the README in the new nested suites test (which doesn't exist on develop yet)

Got it, thanks. I added it as a suggestion so that we can add it before merging and don't forget.

@climbfuji Does this mean this PR needs an update after the merge from develop?

Done in cdb180a