Pin the indd dependency by rev, as every other git dependency is (#1599)

`indd` was the one git dependency taken from a branch:

    indd = { git = "https://github.com/storytold/indd-utils", branch = "main" }

`Cargo.lock` pinned a commit, but any `cargo update` -- and `.github/dependabot.yml`
runs them -- pulls whatever is on that branch into a parser of untrusted INDD
files, with no review of what changed. The craft-libs dependencies beside it are
all `rev = "b926b5c0..."`.

Pinned to `7f3060e5bce78d21ea70e0d5eacb96edce15dfbe`, which is the commit the
lock already held: the only change in `Cargo.lock` is the source string,
`?branch=main` to `?rev=7f3060e5...`, so no code moves with this.

Verified: `cargo check --locked -p designcraft-engine` passes, and
`indd_files_go_through_the_converter_and_its_errors_are_open_errors` still
passes, so the converter is the same one.

Audit DC-18.

Cargo.lock

@@ -3120,7 +3120,7 @@ checksum = "09e54e57b4c48b40f7aec75635392b12b3421fa26fe8b4332e63138ed278459c"
 [[package]]
 name = "indd"
 version = "0.1.0"
-source = "git+https://github.com/storytold/indd-utils?branch=main#7f3060e5bce78d21ea70e0d5eacb96edce15dfbe"
+source = "git+https://github.com/storytold/indd-utils?rev=7f3060e5bce78d21ea70e0d5eacb96edce15dfbe#7f3060e5bce78d21ea70e0d5eacb96edce15dfbe"
 
 [[package]]
 name = "indexmap"

Cargo.toml

@@ -75,9 +75,12 @@ flo_curves = "0.8"
 qrcodegen = "1.8"
 quick-xml = "0.41"
 zip = { version = "3", default-features = false, features = ["deflate"] }
-# INDD/INDT → IDML conversion for File › Open: storytold/indd-utils, tracking its main branch
+# INDD/INDT → IDML conversion for File › Open: storytold/indd-utils, pinned by rev as every other
+# git dependency here is. It parses untrusted INDD files, and `branch = "main"` meant any
+# `cargo update` -- Dependabot runs them -- pulled whatever was on that branch into the parser
+# without review (#1599).
 # (MIT OR Apache-2.0, no dependencies, builds for wasm).
-indd = { git = "https://github.com/storytold/indd-utils", branch = "main" }
+indd = { git = "https://github.com/storytold/indd-utils", rev = "7f3060e5bce78d21ea70e0d5eacb96edce15dfbe" }
 
 # Which paths stored in documents may be followed (craft-libs).
 craft-docpath = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "b926b5c03e256c86ca10934f58d03f628810b5b7" }