regression.yml workflow should run on x86_64 (ubuntu-latest)

Signed-off-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>

Author: martin-g

.github/workflows/regression.yml

@@ -9,11 +9,6 @@ on:
     branches: 
       - 'develop'
       - 'master'
-  workflow_call:
-    # workflows: ["Regression and Unit Post-Validation on Linux ARM64"]
-    # types: [requested]
-    # branches:
-      # - 'develop'
 
 jobs:
   build:
@@ -41,7 +36,7 @@ jobs:
             flags: '-Denable-autodiff=true -Denable-normal=false -Dwith-omp=true -Denable-mixedprec=true -Denable-tecio=false --warnlevel=3 --werror'
           - config_set: ForwardOMP
             flags: '-Denable-directdiff=true -Denable-normal=false -Dwith-omp=true -Denable-mixedprec=true -Denable-tecio=false --warnlevel=3 --werror'
-    runs-on: self-hosted
+    runs-on: ubuntu-latest
     steps:
       - name: Cache Object Files
         uses: actions/cache@v3
@@ -71,7 +66,7 @@ jobs:
           entrypoint: /bin/rm
           args: -rf install install_bin.tgz src ccache ${{ matrix.config_set }}
   regression_tests:
-    runs-on: self-hosted
+    runs-on: ubuntu-latest
     name: Regression Tests
     needs: build
     strategy:
@@ -133,7 +128,7 @@ jobs:
           entrypoint: /bin/rm
           args: -rf install install_bin.tgz src ccache ${{ matrix.config_set }}
   unit_tests:
-    runs-on: self-hosted
+    runs-on: ubuntu-latest
     name: Unit Tests
     needs: build
     strategy: