chore(nix-compat): bump to nom 8.x

See 72dd5818b7/CHANGELOG.md
for the nom changelog.

Most notably, there's now a .parse() to be added:

`combinator(arg)(input)` -> `combinator(arg).parse(input)`

There also doesn't need to be a tuple combinator (it's implemented on
tuples directly).

This also refactors the string / byte field parsing parts, to make them
more concise.

Change-Id: I9e8a3cedd07d6705be391898eb6a486fb8164069
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13193
Tested-by: BuildkiteCI
Reviewed-by: edef <edef@edef.eu>
Reviewed-by: Brian Olsen <me@griff.name>

users/edef/fetchroots/Cargo.lock

@@ -1634,12 +1634,6 @@ dependencies = [
  "libmimalloc-sys",
 ]
 
-[[package]]
-name = "minimal-lexical"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
-
 [[package]]
 name = "miniz_oxide"
 version = "0.7.2"
@@ -1721,12 +1715,11 @@ dependencies = [
 
 [[package]]
 name = "nom"
-version = "7.1.3"
+version = "8.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+checksum = "df9761775871bdef83bee530e60050f7e54b1105350d6884eb0fb4f46c2f9405"
 dependencies = [
  "memchr",
- "minimal-lexical",
 ]
 
 [[package]]