Revert "Using environment variable ImageOS so that installation packages (zip file) have a unique name in from Github Action."

This reverts commit 8c5b003.
Created issue actions/upload-artifact#231

Author: end2endzone

.github/workflows/build_linux.yml

@@ -113,5 +113,5 @@ jobs:
     - name: Archive installation packages
       uses: actions/upload-artifact@v2
       with:
-        name: bin2cpp-packages-${{env.ImageOS}}
+        name: Installation packages.
         path: build/bin2cpp-${{env.BIN2CPP_VERSION}}-*.*

.github/workflows/build_macos.yml

@@ -113,5 +113,5 @@ jobs:
     - name: Archive installation packages
       uses: actions/upload-artifact@v2
       with:
-        name: bin2cpp-packages-${{env.ImageOS}}
+        name: Installation packages.
         path: build/bin2cpp-${{env.BIN2CPP_VERSION}}-*.*

.github/workflows/build_windows.yml

@@ -116,5 +116,5 @@ jobs:
     - name: Archive installation packages
       uses: actions/upload-artifact@v2
       with:
-        name: bin2cpp-packages-${{env.ImageOS}}
+        name: Installation packages.
         path: build/bin2cpp-${{env.BIN2CPP_VERSION}}-*.*