tyxml-ppx.4.6.0: allow ppxlib 0.36 and 0.37

[davesnx]

No description provided.

[jmid]

With the relaxed ppxlib bound I see this failing across the board (0 workflows passed), e.g.
https://opam.ci.ocaml.org/github/ocaml/opam-repository/commit/e9243d54b894f2ff7d6624033a71869eda8f9a19/variant/compilers,5.4,tyxml-ppx.4.6.0

[...]
-> installed ppxlib.0.37.0
-> installed tyxml-syntax.4.6.0
[ERROR] The compilation of tyxml-ppx.4.6.0 failed at "dune build -p tyxml-ppx -j 71 @install".

#=== ERROR while compiling tyxml-ppx.4.6.0 ====================================#
# context              2.5.0 | linux/x86_64 | ocaml-base-compiler.5.4.0 | pinned(https://github.com/ocsigen/tyxml/releases/download/4.6.0/tyxml-4.6.0.tbz)
# path                 ~/.opam/5.4/.opam-switch/build/tyxml-ppx.4.6.0
# command              ~/.opam/opam-init/hooks/sandbox.sh build dune build -p tyxml-ppx -j 71 @install
# exit-code            1
# env-file             ~/.opam/log/tyxml-ppx-7-a64ed7.env
# output-file          ~/.opam/log/tyxml-ppx-7-a64ed7.out
### output ###
# (cd _build/default && /home/opam/.opam/5.4/bin/ocamlopt.opt -w -40 -safe-string -open Ppxlib -w -9 -g -I ppx/.tyxml_ppx.objs/byte -I ppx/.tyxml_ppx.objs/native -I /home/opam/.opam/5.4/lib/markup -I /home/opam/.opam/5.4/lib/ocaml-compiler-libs/common -I /home/opam/.opam/5.4/lib/ocaml-compiler-libs/shadow -I /home/opam/.opam/5.4/lib/ocaml/compiler-libs -I /home/opam/.opam/5.4/lib/ppx_derivers -I /home/opam/.opam/5.4/lib/ppxlib -I /home/opam/.opam/5.4/lib/ppxlib/ast -I /home/opam/.opam/5.4/lib/ppxlib/astlib -I /home/opam/.opam/5.4/lib/ppxlib/print_diff -I /home/opam/.opam/5.4/lib/ppxlib/stdppx -I /home/opam/.opam/5.4/lib/ppxlib/traverse_builtins -I /home/opam/.opam/5.4/lib/re -I /home/opam/.opam/5.4/lib/re/str -I /home/opam/.opam/5.4/lib/sexplib0 -I /home/opam/.opam/5.4/lib/stdlib-shims -I /home/opam/.opam/5.4/lib/tyxml-syntax -I /home/opam/.opam/5.4/lib/uutf -cmi-file ppx/.tyxml_ppx.objs/byte/tyxml_ppx.cmi -no-alias-deps -o ppx/.tyxml_ppx.objs/native/tyxml_ppx.cmx -c -impl ppx/tyxml_ppx.pp.ml)
# File "ppx/tyxml_ppx.ml", line 381, characters 4-12:
# 381 |   | Pexp_fun (label,def,pat,content) ->
#           ^^^^^^^^
# Error: This variant pattern is expected to have type
#          Ppxlib.Parsetree.expression_desc
#        There is no constructor Pexp_fun within type Ppxlib.Parsetree.expression_desc
# Hint:             Did you mean Pexp_for?
# (cd _build/default && /home/opam/.opam/5.4/bin/ocamlc.opt -w -40 -safe-string -open Ppxlib -w -9 -g -bin-annot -bin-annot-occurrences -I ppx/.tyxml_ppx.objs/byte -I /home/opam/.opam/5.4/lib/markup -I /home/opam/.opam/5.4/lib/ocaml-compiler-libs/common -I /home/opam/.opam/5.4/lib/ocaml-compiler-libs/shadow -I /home/opam/.opam/5.4/lib/ocaml/compiler-libs -I /home/opam/.opam/5.4/lib/ppx_derivers -I /home/opam/.opam/5.4/lib/ppxlib -I /home/opam/.opam/5.4/lib/ppxlib/ast -I /home/opam/.opam/5.4/lib/ppxlib/astlib -I /home/opam/.opam/5.4/lib/ppxlib/print_diff -I /home/opam/.opam/5.4/lib/ppxlib/stdppx -I /home/opam/.opam/5.4/lib/ppxlib/traverse_builtins -I /home/opam/.opam/5.4/lib/re -I /home/opam/.opam/5.4/lib/re/str -I /home/opam/.opam/5.4/lib/sexplib0 -I /home/opam/.opam/5.4/lib/stdlib-shims -I /home/opam/.opam/5.4/lib/tyxml-syntax -I /home/opam/.opam/5.4/lib/uutf -cmi-file ppx/.tyxml_ppx.objs/byte/tyxml_ppx.cmi -no-alias-deps -o ppx/.tyxml_ppx.objs/byte/tyxml_ppx.cmo -c -impl ppx/tyxml_ppx.pp.ml)
# File "ppx/tyxml_ppx.ml", line 381, characters 4-12:
# 381 |   | Pexp_fun (label,def,pat,content) ->
#           ^^^^^^^^
# Error: This variant pattern is expected to have type
#          Ppxlib.Parsetree.expression_desc
#        There is no constructor Pexp_fun within type Ppxlib.Parsetree.expression_desc
# Hint:             Did you mean Pexp_for?

So I think we can conclude it doesn't work with ppxlib.0.37.
Perhaps we can get away with ppxlib.0.36 though? 🤔