CI: Fix FFmpeg build GitHub action cache save condition #247

Job	Run time
Run Pre-Checks	3s
Build FFmpeg for Windows (x64)	2m 57s
Build FFmpeg for Windows (x86)	3m 10s
Build Qt6 (macOS)	8m 56s
Build FFmpeg for macOS (macos-arm64)	4m 3s
Build macOS Dependencies (macos-arm64)	9m 45s
Build FFmpeg for macOS (macos-x86_64)	3m 51s
Build macOS Dependencies (macos-x86_64)	6m 12s
Build Qt6 (Windows) (x64, RelWithDebInfo)	3m 5s
Build Qt6 (Windows) (x64, Debug)	3m 28s
Build Windows Dependencies (x64)	3m 4s
Build Qt6 (Windows) (x86, RelWithDebInfo)	3m 13s
Build Windows Dependencies (x86)	1m 58s
Build Qt6 (Windows) (x86, Debug)	2m 59s
Package Windows Qt6 (x64)	3m 29s
Package Windows Qt6 (x86)	3m 21s
Build FFmpeg (Universal)	2m 52s
Create macOS Qt6 (macos-arm64)	3m 56s
Create macOS Qt6 (macos-x86_64)	4m 43s
Build macOS Dependencies (Universal)	1m 54s
Create and upload release	0s
	1h 16m 59s

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