Disable cache-on-failure (save-always: false on julia-actions/cache@v3) (#119)

## Summary

`julia-actions/cache@v3` (introduced via #118) saves caches **on job
failure** by default, where v2 only saved on success. The escape hatch
documented in the v3 release notes is `save-always: false`. This PR sets
that on every `julia-actions/cache@v3` invocation in the reusable
workflows here.

The new v3 default is reasonable for the common case (test-failure
retries reuse the expensive depot install). But when the failure is in
the *setup* itself — a half-installed depot, an aborted `Pkg` precompile
— the broken state is cached, the restore-key prefix matches subsequent
runs, and every retry restores the broken state and fails identically.
Reruns alone can't recover; the cache has to be manually evicted or
expire.

This was hit on
[`ITensor/ITensorNetworks.jl#373`](ITensor/ITensorNetworks.jl#373):
a fresh Windows run failed in `Pkg.test` precompilation (`ChainRulesCore
is required but does not seem to be installed`), the broken state was
cached, and two reruns reproduced the failure verbatim by restoring from
that cache.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mtfishman

.github/workflows/CheckCompatBounds.yml

@@ -74,6 +74,9 @@ jobs:
         if: "${{ inputs.cache }}"
         with:
           token: "${{ secrets.GITHUB_TOKEN }}"
+          # See the comment in `Tests.yml`: don't cache a failed job's
+          # half-installed depot, which would otherwise poison the cache.
+          save-always: false
 
       - uses: julia-actions/julia-buildpkg@v1
         if: "${{ inputs.buildpkg }}"

.github/workflows/Documentation.yml

@@ -98,6 +98,9 @@ jobs:
         if: "${{ inputs.cache }}"
         with:
           token: "${{ secrets.GITHUB_TOKEN }}"
+          # See the comment in `Tests.yml`: don't cache a failed job's
+          # half-installed depot, which would otherwise poison the cache.
+          save-always: false
 
       - name: "Export extra environment variables"
         if: "${{ inputs.extra-env != '' }}"

.github/workflows/FormatCheck.yml

@@ -64,6 +64,10 @@ jobs:
           arch: "x64"
 
       - uses: julia-actions/cache@v3
+        with:
+          # See the comment in `Tests.yml`: don't cache a failed job's
+          # half-installed depot, which would otherwise poison the cache.
+          save-always: false
 
       - name: "Install ITensorFormatter"
         run: |

.github/workflows/FormatPullRequest.yml

@@ -54,6 +54,10 @@ jobs:
           arch: "${{ runner.arch }}"
 
       - uses: julia-actions/cache@v3
+        with:
+          # See the comment in `Tests.yml`: don't cache a failed job's
+          # half-installed depot, which would otherwise poison the cache.
+          save-always: false
 
       - name: "Install ITensorFormatter"
         run: |

.github/workflows/Registrator.yml

@@ -76,6 +76,9 @@ jobs:
       - uses: julia-actions/cache@v3
         with:
           delete-old-caches: false
+          # See the comment in `Tests.yml`: don't cache a failed job's
+          # half-installed depot, which would otherwise poison the cache.
+          save-always: false
 
       - name: "Checkout package"
         uses: actions/checkout@v6

.github/workflows/Tests.yml

@@ -180,6 +180,11 @@ jobs:
         if: "${{ steps.classify.outputs.triggers == 'true' && inputs.cache }}"
         with:
           token: "${{ secrets.GITHUB_TOKEN }}"
+          # Restore the pre-v3 behavior: don't save a cache from a failed
+          # job. v3 caches on failure by default, which poisons the cache
+          # with broken state (e.g. a half-installed depot) and makes every
+          # subsequent run restore that broken state and fail the same way.
+          save-always: false
 
       - uses: julia-actions/julia-buildpkg@v1
         if: "${{ steps.classify.outputs.triggers == 'true' && inputs.buildpkg }}"