[Fix] ci: Allow manual builds, shorten name

Allow triggering manual builds in case dependencies change, artifacts
expire or get deleted, etc.

Shorten the workflow name to "Build PyInstaller" to be easier to read
on GitHub's mobile site.

See https://docs.github.com/en/actions/using-workflows/manually-running-a-workflow

.github/workflows/build-pyinstaller.yml → .github/workflows/build-pyinstall.yml

@@ -1,15 +1,23 @@
-name: Build with PyInstaller
-
-# From https://github.com/sayyid5416/pyinstaller
+name: Build PyInstall
+# Based on https://github.com/sayyid5416/pyinstaller
 
 on:
-  push:
-  pull_request:
+  # All branches:
+  [ push, pull_request, workflow_dispatch ]
+  # "main" only:
+  #push:
+  #  branches: [ "main" ]
+  #pull_request:
+  #  branches: [ "main" ]
+  #workflow_dispatch:
+  #  branches: [ "main" ]
 
 # Get git tag info via GitHub API due to shallow clone:
-# See https://github.com/marketplace/actions/gh-describe
-# And https://stackoverflow.com/questions/66349002/get-latest-tag-git-describe-tags-when-repo-is-cloned-with-depth-1
-# And https://dev.to/hectorleiva/github-actions-and-creating-a-short-sha-hash-8b7
+# See...
+#     https://github.com/marketplace/actions/gh-describe
+# Alongside these resources, not used here:
+#     https://stackoverflow.com/questions/66349002/get-latest-tag-git-describe-tags-when-repo-is-cloned-with-depth-1
+#     https://dev.to/hectorleiva/github-actions-and-creating-a-short-sha-hash-8b7
 
 jobs:
   pyinstall-windows: