Use dev texmath, update stack.yaml resolver.

cabal.project

@@ -7,3 +7,7 @@ flags: +embed_data_files
 constraints: skylighting-format-blaze-html >= 0.1.1,
              skylighting-format-context >= 0.1.0.2
 
+source-repository-package
+  type: git
+  location: https://github.com/jgm/texmath
+  tag: 0a7b5a58e1969d93e18ff7d39f8375098e21300b

stack.yaml

@@ -19,18 +19,15 @@ extra-deps:
 - crypton-x509-system-1.6.7
 - crypton-x509-validation-1.6.12
 - http-client-tls-0.3.6.2
-- commonmark-0.2.3
 - typst-symbols-0.1.2
 - toml-parser-1.3.0.0
-- xml-conduit-1.9.1.3
-- commonmark-extensions-0.2.3.5
 - typst-0.3.1.0
-- skylighting-core-0.13.4.1
-- skylighting-0.13.4.1
-- pandoc-types-1.23.1
+- git: https://github.com/jgm/texmath
+  commit: 0a7b5a58e1969d93e18ff7d39f8375098e21300b
+
 ghc-options:
    "$locals": -fhide-source-paths -Wno-missing-home-modules
-resolver: lts-21.0
+resolver: lts-21.7
 nix:
   packages:
   - pkg-config