Add Additional SPM Build Targets (#3570)

* Add additional SPM targets.

* Update package versioning.

* Separate out SPM testing.

.github/workflows/ci.yml

@@ -196,7 +196,7 @@ jobs:
     name: Test with SPM
     runs-on: macOS-11
     env:
-      DEVELOPER_DIR: /Applications/Xcode_13.2.1.app/Contents/Developer
+      DEVELOPER_DIR: "/Applications/Xcode_13.2.1.app/Contents/Developer"
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v2
@@ -204,6 +204,28 @@ jobs:
         run: brew install alamofire/alamofire/firewalk && firewalk &
       - name: Test SPM
         run: swift test -c debug
+  SPM_Older:
+    name: Test with SPM
+    runs-on: ${{ matrix.runsOn }}
+    env:
+      DEVELOPER_DIR: "/Applications/${{ matrix.xcode }}/Contents/Developer"
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - xcode: "Xcode_12.5.1.app"
+            runsOn: macOS-11
+            name: "macOS 11, SPM 5.4 Build"
+          - xcode: "Xcode_12.4.app"
+            runsOn: macOS-10.15
+            name: "macOS 10.15, SPM 5.3 Build"
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Firewalk
+        run: brew install alamofire/alamofire/firewalk && firewalk &
+      - name: Test SPM
+        run: swift build -c debug
   Linux:
     name: Linux
     runs-on: ubuntu-20.04