GHA CI: compress debug symbols

The result binary is smaller.

.github/workflows/ci_macos.yaml

@@ -87,6 +87,7 @@ jobs:
         if: ${{ startsWith(matrix.qt_version, 5) }}
         run: |
           CXXFLAGS="$CXXFLAGS -Werror -Wno-error=deprecated-declarations" \
+          LDFLAGS="$LDFLAGS -gz" \
           cmake \
             -B build \
             -G "Ninja" \
@@ -105,6 +106,7 @@ jobs:
         if: ${{ startsWith(matrix.qt_version, 6) }}
         run: |
           CXXFLAGS="$CXXFLAGS -Wno-gnu-zero-variadic-macro-arguments -Werror -Wno-error=deprecated-declarations" \
+          LDFLAGS="$LDFLAGS -gz" \
           cmake \
             -B build \
             -G "Ninja" \

.github/workflows/ci_ubuntu.yaml

@@ -69,6 +69,7 @@ jobs:
         if: ${{ startsWith(matrix.qt_version, 5) }}
         run: |
           CXXFLAGS="$CXXFLAGS -Werror -Wno-error=deprecated-declarations" \
+          LDFLAGS="$LDFLAGS -gz" \
           cmake \
             -B build \
             -G "Ninja" \
@@ -87,6 +88,7 @@ jobs:
         if: ${{ startsWith(matrix.qt_version, 6) }}
         run: |
           CXXFLAGS="$CXXFLAGS -Werror" \
+          LDFLAGS="$LDFLAGS -gz" \
           cmake \
             -B build \
             -G "Ninja" \