[Swift] Sets Swift minimum support to 5.8 #5929

Job	Run time
Build Dart	38s
Build Benchmarks (on Linux) (g++-13)	1m 44s
Build Windows C++ (11)	3m 20s
Build Android (on Linux)	3m 30s
Build .NET Windows	1m 11s
Build Windows C++ (14)	3m 18s
Build .NET Windows (-p:UnsafeByteBuffer=true)	1m 12s
Check Generated Code (g++-13)	31s
Build Windows C++ (17)	4m 2s
Check Generated Code (clang++-15)	24s
Build Windows C++ (20)	5m 21s
Build Windows C++ (23)	5m 20s
Check Generated Code on Windows	3m 56s
Build Java	25s
Build Go	1m 1s
Build Kotlin Linux	1m 33s
Build Kotlin MacOS	8m 39s
Build Linux (g++-13)	51s
Build Linux C++ (11, g++-13)	31s
Build Linux with -DFLATBUFFERS_NO_FILE_TESTS	49s
Build Linux (clang++-15)	55s
Build Linux C++ (11, clang++-15)	35s
Build Linux with out-of-source build location	23s
Build Linux C++ (14, g++-13)	30s
Build Mac (for Intel)	2m 49s
Build Mac (universal build)	2m 3s
Build Linux C++ (14, clang++-15)	52s
Build Nim	30s
Build Linux C++ (17, g++-13)	32s
Build Linux C++ (17, clang++-15)	48s
Build PHP	28s
Build Rust Linux	1m 14s
Build Linux C++ (20, g++-13)	34s
Build Python	26s
Build Linux C++ (20, clang++-15)	47s
Build Linux C++ (23, g++-13)	33s
Build Rust Windows	1m 23s
Build Swift (5.8)	1m 3s
Build Swift Wasm	1m 46s
Build Swift (5.9)	1m 9s
Build TS	47s
Build Windows 2019	3m 59s
release-digests	0s
provenance	0s
	1h 12m 22s

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