Apply review comment - unify spaces inside the double brackets for variable substitution

Author: sergregory

.github/workflows/build_wheels.yml

@@ -27,7 +27,7 @@ jobs:
 
     env:
       ACTIONS_ALLOW_UNSECURE_COMMANDS: true
-      SDIST: ${{ matrix.build_sdist || 0}}
+      SDIST: ${{ matrix.build_sdist || 0 }}
       ENABLE_HEADLESS: ${{ matrix.without_gui }}
       ENABLE_CONTRIB: ${{ matrix.with_contrib }}
 
@@ -108,7 +108,7 @@ jobs:
       DOCKER_IMAGE: quay.io/skvark/manylinux2014_${PLAT}
       USE_CCACHE: 1
       UNICODE_WIDTH: 32
-      SDIST: ${{ matrix.build_sdist || 0}}
+      SDIST: ${{ matrix.build_sdist || 0 }}
       ENABLE_HEADLESS: ${{ matrix.without_gui }}
       ENABLE_CONTRIB: ${{ matrix.with_contrib }}
 
@@ -197,9 +197,9 @@ jobs:
       DOCKER_IMAGE: quay.io/skvark/manylinux2014_${PLAT}
       USE_CCACHE: 1
       UNICODE_WIDTH: 32
-      SDIST: ${{ matrix.build_sdist || 0}}
+      SDIST: ${{ matrix.build_sdist || 0 }}
       ENABLE_HEADLESS: ${{ matrix.without_gui || 0 }}
-      ENABLE_CONTRIB: ${{ matrix.with_contrib || 0}}
+      ENABLE_CONTRIB: ${{ matrix.with_contrib || 0 }}
 
     steps:
     - name: Checkout