Fix downgrade CI: run downgrade leg on Julia 1.11 + raise PrecompileTools/TruncatedStacktraces floors

The Downgrade (Core) job was red on lts (Julia 1.10). Three distinct, genuine
problems, fixed at their causes:

1. Unsatisfiable resolution. The resolver (julia-downgrade-compat -> Resolver.jl)
   minimizes Julia to the floor of its --julia range; on lts that range (1.10)
   admits 1.10.0. But every Mooncake 0.5.x test extra requires julia >= 1.10.8,
   so Mooncake can never be placed -> Unsatisfiable. Even at 1.10.8 the
   Enzyme 0.13 + EnzymeCore 0.8 + Mooncake 0.5 minimum-version set has no
   solution on the 1.10 LTS stdlib line; it resolves only once Julia reaches
   1.11.6 (Mooncake 0.5's 1.11 floor). Resolver.jl ignores the project's
   [compat] julia for the Julia version itself, so no Project.toml change can
   force julia >= 1.10.8 -- the caller must request it. Fix: pin the Downgrade
   caller to julia-version "1.11" (resolver picks 1.11.6). Core 1.10 support is
   still exercised by the regular Tests workflow.

2. PrecompileTools floor too low. With resolution fixed, the minimum
   PrecompileTools 1.0.0 fails to precompile GPUCompiler (pulled transitively by
   Enzyme) on Julia 1.11: "UndefVarError: PrecompileTools not defined in
   GPUCompiler". GPUCompiler's compat says PrecompileTools "1", but 1.0.0 does
   not actually provide the API GPUCompiler uses; 1.1.0 does. Raise the floor
   to "1.1".

3. TruncatedStacktraces floor too low. src uses
   TruncatedStacktraces.@truncate_stacktrace, which does not exist before v1.1.0
   ("UndefVarError: @truncate_stacktrace not defined in TruncatedStacktraces" at
   the v1.0.0 floor). Raise the floor to "1.1".

Also reverts the earlier misdiagnosed FunctionWrappers floor raise (1 -> 1.1.3):
no registered test dep constrains FunctionWrappers and the source only uses the
FunctionWrapper{R,A} constructor available since 1.0.0. Version bumped to 1.9.2
for the compat-floor changes.

Local verification on Julia 1.11 (the new downgrade leg): the actual
julia-downgrade-compat downgrade.jl resolves the merged test project (exit 0,
"Successfully resolved minimal versions"); the downgraded manifest (Enzyme
0.13.0 / GPUCompiler 0.27.5 / PrecompileTools 1.1.0 / TruncatedStacktraces 1.1.0
/ Mooncake 0.5.0) precompiles cleanly; and Pkg.test GROUP=Core passes
(FunctionWrappersWrappers.jl 48/48, BigFloat + UnionAll 7/7).

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas

.github/workflows/Downgrade.yml

@@ -28,5 +28,13 @@ jobs:
     uses: "SciML/.github/.github/workflows/downgrade.yml@v1"
     with:
       group: "${{ matrix.group }}"
-      julia-version: "lts"
+      # The Mooncake/Enzyme test extras only resolve at their declared minimum
+      # versions on Julia >= 1.11.6: every Mooncake 0.5.x requires julia >= 1.10.8,
+      # and the Enzyme 0.13 + EnzymeCore 0.8 + Mooncake 0.5 floor set has no
+      # minimum-version solution on the 1.10 LTS stdlib line. The downgrade
+      # resolver minimizes julia to the floor of its --julia range, so on lts
+      # (=1.10, which admits 1.10.0) it strands Mooncake -> Unsatisfiable. Pin the
+      # downgrade leg to 1.11 (resolves to julia 1.11.6); the core package's 1.10
+      # support is still exercised by the regular Tests workflow.
+      julia-version: "1.11"
     secrets: "inherit"

Project.toml

@@ -20,12 +20,12 @@ FunctionWrappersWrappersMooncakeExt = "Mooncake"
 [compat]
 Enzyme = "0.13"
 EnzymeCore = "0.8"
-FunctionWrappers = "1.1.3"
+FunctionWrappers = "1"
 Mooncake = "0.5"
-PrecompileTools = "1"
+PrecompileTools = "1.1"
 SafeTestsets = "0.1, 1"
 SciMLTesting = "1"
-TruncatedStacktraces = "1"
+TruncatedStacktraces = "1.1"
 julia = "1.10"
 
 [extras]