woodpecker: use parallel build groups

.woodpecker.yml

@@ -1,18 +1,22 @@
 pipeline:
-  build:
+  build_bike:
     group: build
     image: python
     commands:
       - pip install -U platformio
-      - pio run -e ${VARIANT}
-      - pio run -e ${VARIANT} --target buildfs
-matrix:
-  VARIANT:
-    - bike
-    - bike_ble
-    - esp32
-    - esp32_wifi
-    - esp32_bluetooth
-    - esp8266_wifi
-    - esp8266
-    - esp8266-12f
+      - pio run -e bike -e bike_ble
+      - pio run -e bike -e bike_ble --target buildfs
+  build_esp32:
+    group: build
+    image: python
+    commands:
+      - pip install -U platformio
+      - pio run -e esp32 -e esp32_wifi -e esp32_bluetooth
+      - pio run -e esp32 -e esp32_wifi -e esp32_bluetooth --target buildfs
+  build_8266:
+    group: build
+    image: python
+    commands:
+      - pip install -U platformio
+      - pio run -e esp8266 -e esp8266_wifi
+      - pio run -e esp8266 -e esp8266_wifi --target buildfs