Update minimum CMake to v3.10

[hjmallon]

• I've checked this Git style guide. [Yes]
• I've checked this CMake style guide. [Yes]
• My change will work with CMake 3.5 (minimum requirement for Hunter). [No]
• I will try to keep this pull request as small as possible and will try not to mix unrelated features. [Yes]

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Also needs a gate update after cpp-pm/gate#18

[Waarbubble]

Is there an ETA on when this can be approved, or where in the progress this is?

[NeroBurner]

minor documentation update and then we're good to go!

Thanks for the PR

[NeroBurner]

Just merged the Gate PR cpp-pm/gate#18
And created a release: https://github.com/cpp-pm/gate/releases/tag/v0.11.0

Could you update the gate submodule to that tag as well in this PR please

[hjmallon]

I have updated the gate submodule and also found some more places in examples where the older version was set

[chfast]

How are we doing here?

[NeroBurner]

looking good! Thanks for the update and the sensible format and trailing line fixes

[chfast]

After this is merged, can we get a new release?

[NeroBurner]

yes, I just want to finish #780 such that the CI-toolchains work again and are updated

[NeroBurner]

Released: https://github.com/cpp-pm/hunter/releases/tag/v0.26.0