fix: is_hex checks if a string begins with 0x #527

Job	Run time
🚨 REUSE Compliance	16s
🚨 C lint	23s
🚨 Lua lint	20s
🐍 Python checks (ubuntu-latest, 3.8)	2m 13s
🐍 Python checks (ubuntu-latest, 3.9)	1m 48s
🐍 Python checks (ubuntu-latest, 3.10)	2m 16s
🐍 Python checks (macos-latest, 3.8)	4m 1s
🐍 Python checks (macos-latest, 3.9)	3m 40s
🐍 Python checks (macos-latest, 3.10)	3m 39s
🐯 js build & checks (14.x)	3m 38s
🐯 js build & checks (16.x)	3m 16s
🐯 js build & checks (18.x)	3m 25s
🐹 go build & checks (1.13)	1m 18s
🐹 go build & checks (1.14)	1m 24s
🐹 go build & checks (1.15)	1m 28s
🐹 go build & checks (1.16)	1m 36s
🐹 go build & checks (1.19)	1m 18s
🥷 meson/ninja build (clang-9)	7m 42s
🥷 meson/ninja build (clang-10)	2m 7s
🥷 meson/ninja build (clang-11)	1m 48s
🥷 meson/ninja build (gcc-7)	2m 24s
🥷 meson/ninja build (gcc-8)	3m 0s
🥷 meson/ninja build (gcc-9)	2m 29s
🥷 meson/ninja build (gcc-10)	2m 7s
🦀 rust build & checks (stable)	1m 49s
🦀 rust build & checks (nightly)	1m 56s
🤖 Semantic release	0s
🐧 Binary builds on Ubuntu	0s
🐍 Python build & checks	0s
🍎 mac osx release build	0s
📦 npm release	0s
🐍 Python build & check on armv7	0s
🐍 Python create source distribution	0s
📦 PyPI release	0s
📦 Pack release	0s
	1h 1m 21s

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