CI: github: add 'workflow_dispatch' on remaining build jobs

Add 'workflow_dispatch' on the remaining scheduled build jobs that does
not have it.

This keyword allows to start manually a job from the "Actions" interface
in github.

.github/workflows/cross-zoo.yml

@@ -6,6 +6,7 @@ name: Cross Compile
 on:
   schedule:
     - cron: "0 0 21 * *"
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/fedora-rawhide.yml

@@ -3,6 +3,7 @@ name: Fedora/Rawhide/QuicTLS
 on:
   schedule:
     - cron: "0 0 25 * *"
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/netbsd.yml

@@ -3,6 +3,7 @@ name: NetBSD
 on:
   schedule:
     - cron: "0 0 25 * *"
+  workflow_dispatch:
 
 jobs:
   gcc:

.github/workflows/openssl-nodeprecated.yml

@@ -13,6 +13,7 @@ name: openssl no-deprecated
 on:
   schedule:
   - cron: "0 0 * * 4"
+  workflow_dispatch:
 
 permissions:
   contents: read