“Miss Juneteenth” richly captures the slow pace of ebbing small-town Texas life, even if you might wish there were a bit more narrative momentum to pick up the slack in writer-director Channing Godfrey People’s first feature. She’s got a very relatable heroine in Nicole Beharie’s Turquoise, an erstwhile local beauty queen whose crown proved the peak rather than the kickoff to her dream of a better life — high hopes now transferred to a daughter reluctant to inherit that burden.