fix: include .lake in artifact upload (leanprover-community#28092)

Follow-up to leanprover-community#28062. It turns out `.olean` files are stored in `.lake` which are excluded by default by the `actions/upload-artifact` action. We use the `include-hidden-files` option, taking care to exclude the `.git` folder which may include secrets like `GITHUB_TOKEN`, etc.

Author: bryangingechen

.github/build.in.yml

@@ -267,7 +267,11 @@ jobs:
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: mathlib4_artifact
-          path: pr-branch/
+          include-hidden-files: true
+          # we exclude .git since there may be secrets in there
+          path: |
+            pr-branch/
+            !pr-branch/.git/
 
       # The cache secrets are available here, so we must not run any untrusted code.
       - name: upload cache

.github/workflows/bors.yml

@@ -277,7 +277,11 @@ jobs:
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: mathlib4_artifact
-          path: pr-branch/
+          include-hidden-files: true
+          # we exclude .git since there may be secrets in there
+          path: |
+            pr-branch/
+            !pr-branch/.git/
 
       # The cache secrets are available here, so we must not run any untrusted code.
       - name: upload cache

.github/workflows/build.yml

@@ -284,7 +284,11 @@ jobs:
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: mathlib4_artifact
-          path: pr-branch/
+          include-hidden-files: true
+          # we exclude .git since there may be secrets in there
+          path: |
+            pr-branch/
+            !pr-branch/.git/
 
       # The cache secrets are available here, so we must not run any untrusted code.
       - name: upload cache

.github/workflows/build_fork.yml

@@ -281,7 +281,11 @@ jobs:
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: mathlib4_artifact
-          path: pr-branch/
+          include-hidden-files: true
+          # we exclude .git since there may be secrets in there
+          path: |
+            pr-branch/
+            !pr-branch/.git/
 
       # The cache secrets are available here, so we must not run any untrusted code.
       - name: upload cache