fix: pin GitHub Actions to SHA hashes #1

Job	Run time
Test - stable toolchain (minimal)	14m 40s
Prepare	5s
Test - stable toolchain (recent)	15m 9s
Embedded	3m 46s
Docs - stable toolchain (recent)	1m 1s
Test - 1.63.0 toolchain (minimal)	30m 35s
Integration tests - stable toolchain (25_2)	1m 20s
Integration tests - stable toolchain (25_1)	1m 5s
Integration tests - stable toolchain (26_0)	1m 28s
Test - 1.63.0 toolchain (recent)	29m 32s
Integration tests - stable toolchain (25_0)	56s
Integration tests - stable toolchain (23_2)	1m 2s
Integration tests - stable toolchain (24_0_1)	2m 0s
Integration tests - stable toolchain (24_2)	1m 0s
Integration tests - stable toolchain (0_19_1)	50s
Integration tests - stable toolchain (22_1)	53s
Integration tests - stable toolchain (23_1)	52s
Integration tests - stable toolchain (23_0)	1m 31s
Integration tests - stable toolchain (0_18_1)	4m 39s
Integration tests - stable toolchain (0_20_2)	57s
Integration tests - stable toolchain (24_1)	1m 46s
Integration tests - stable toolchain (22_0)	4m 1s
Integration tests - stable toolchain (0_21_2)	1m 25s
Integration tests - stable toolchain (0_17_1)	1m 0s
Bench - nightly toolchain (recent)	3m 22s
Format - nightly toolchain	14s
Lint - nightly toolchain (recent)	51s
Docs - nightly toolchain (recent)	46s
Test - nightly toolchain (minimal)	14m 48s
Test - nightly toolchain (recent)	15m 9s
	2h 36m 43s

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