Fix yaml syntax.

.github/workflows/nuget.yml

@@ -5,8 +5,6 @@ on: pull_request
 jobs:
   build:
     runs-on: windows-latest
-    strategy:
-      matrix:
 
     steps:
     - uses: actions/checkout@v2

.github/workflows/tag.yml

@@ -5,8 +5,6 @@ on: pull_request
 jobs:
   build:
     runs-on: windows-latest
-    strategy:
-      matrix:
 
     steps:
     - uses: actions/checkout@v2

.github/workflows/windows.yml

@@ -9,27 +9,11 @@ jobs:
       matrix:
         # windows-2016 and windows-2019 have MSVC 2017 and 2019 installed
         # respectively: https://github.com/actions/virtual-environments.
-        os: [windows-2016, windows-2019]
+        os: [windows-2019, windows-latest]
         platform: [Win32, x64]
         build_type: [Debug, Release]
         standard: [11, 17, 20]
-        include:
-          - os: windows-2016
-            platform: Win32
-            build_type: Debug
-            shared: -DBUILD_SHARED_LIBS=ON
-        exclude:
-          - os: windows-2016
-            platform: Win32
-          - os: windows-2016
-            standard: 17
-          - os: windows-2016
-            standard: 20
-          - os: windows-2019
-            standard: 11
-          - os: windows-2019
-            standard: 20
-            platform: Win32
+        shared: [ -DBUILD_SHARED_LIBS=ON ]
 
     steps:
     - uses: actions/checkout@v2