Fixes the build on Xcode 14.3b2

[dymv]

What behavior was changed?

None.

What code was refactored / updated to support this change?

Updates made to ObjC func implementations. More info: https://developer.apple.com/forums/thread/725753

What issues are related to this PR? Or why was this change introduced?

Building Nimble in Xcode 14.3b2 (14E5207e) is failing due to

.../nimble/Sources/NimbleObjectiveC/DSL.m:71:41: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
NIMBLE_EXPORT NMBPredicate *NMB_beTruthy() {
                                        ^
                                         void

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• [x] Does this have tests? — NO
• [x] Does this have documentation? — NO
• [x] Does this break the public API (Requires major version bump)? — NO
• [x] Is this a new feature (Requires minor version bump)? — NO

[dymv]

Thank you @younata 🙇

[einar-notland]

@younata Any plans for a release with this included? I mean now that Xcode 14.3 is out of beta.

[younata]

@younata Any plans for a release with this included? I mean now that Xcode 14.3 is out of beta.

Thanks for the reminder! v11.2.2 is now released and includes this fix!