fix: skip existing releases in marketplace workflow #178

Job	Run time
Skit / Lint (fmt + clippy)	5m 0s
Skit / Build	12m 48s
E2E / Playwright E2E	4m 34s
UI / Build	25s
UI / Lint (TypeScript + ESLint)	41s
UI / Test	20s
Plugins / Lint (Whisper)	40s
Skit / Test	8m 41s
Plugins / Lint (Sherpa-ONNX Plugins)	54s
Plugins / Lint (Simple Plugins)	40s
Plugins / Lint (NLLB)	2m 16s
Plugins / Format Check	19s
All Checks Passed	3s
	37m 21s

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