Don't run Build-Release workflow on every PR, reduce CI overhead (#4726)

---
DESC: Don't run Build-Release workflow on every PR, reduce CI overhead
TYPE: NO_HISTORY

Author: ihnorton

.github/workflows/release.yml

@@ -1,22 +1,13 @@
 name: Release
 
 on:
-  pull_request:
-    branches:
-      - '*'  # must quote since "*" is a YAML reserved character; we want a string
-    paths-ignore:
-      - '.github/workflows/quarto-render.yml'
-      - '_quarto.yml'
-      - 'quarto-materials/*'
-      - '**/.md'
-      - 'tiledb/doxygen/source/*'
-      - 'tiledb/sm/c_api/tiledb_version.h'
   push:
     branches:
       - dev
       - 'release-*'
     tags:
       - '*'
+  workflow_dispatch:
 
 jobs:
   Build-Release:
@@ -58,7 +49,7 @@ jobs:
         uses: actions/checkout@v3
       - name: 'Homebrew setup'
         run: brew install automake pkg-config
-        if: ${{ startsWith(matrix.os, 'macos-') == true }}  
+        if: ${{ startsWith(matrix.os, 'macos-') == true }}
       - name: Export GitHub Actions cache variables
         uses: actions/github-script@v6
         with: