Add space in flag in release notes

[illicitonion]

The = is important as part of the value - 1.2.3 is not an exact version.

[rust-highfive]

r? @ehuss

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[ehuss]

Hm, I'm a bit confused. The note isn't trying to imply that the = is required. From #8022, the tests like already_installed_exact_does_not_update use that same syntax (install foo --version=1.0.0).

Maybe just remove the = to avoid the amibguity?

[illicitonion]

Apologies, you're completely right - I thought that --version took a semver, and forgot that it had special handling for treating 1.2.3 as if it's =1.2.3!