workflows: skip CI on forks

Match the wolfssl repo's convention (see .github/workflows/xcode.yml,
ocsp.yml, etc.): gate each job with
`if: github.repository_owner == 'wolfssl'` so Actions run only for the
upstream repository owner and not for forks pushing their own branches.

Author: julek-wolfssl

.github/workflows/ci.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   build:
+    if: github.repository_owner == 'wolfssl'
     strategy:
       fail-fast: false
       matrix:

.github/workflows/windows-check.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   build:
+    if: github.repository_owner == 'wolfssl'
     runs-on: windows-latest
     timeout-minutes: 10