chore(CI): gitpod dockerfile update

.gitignore

@@ -1,4 +1,5 @@
 *.o
+*.a
 *.iq
 rtlsdr_wsprd
 fftw_wisdom.dat

.gitpod.Dockerfile

@@ -1,6 +1,8 @@
 FROM gitpod/workspace-full
 
-RUN sudo apt-get update && sudo apt-get install -y \
-  valgrind libcmocka-dev cmocka-doc libcmocka0 \
-  build-essential clang cmake \
-  libfftw3-dev libusb-1.0-0-dev librtlsdr-dev libcurl4-gnutls-dev
+RUN sudo apt-get update \
+ && sudo apt-get install -y \
+         valgrind libcmocka-dev cmocka-doc libcmocka0 \
+         build-essential clang cmake \
+         libfftw3-dev libusb-1.0-0-dev librtlsdr-dev libcurl4-gnutls-dev \
+ && sudo rm -rf /var/lib/apt/lists/*