fix string formatting syntax in source.py

gstlal/python/pipeparts/source.py

@@ -355,8 +355,8 @@ def fake(pipeline: pipetools.Pipeline, instrument: str, channel_name: str, block
 	caps = filters.caps(pipeline,
 						audio_test(pipeline, samples_per_buffer=int(blocksize / 8), wave=wave,
 								   volume=volume, is_live=is_live, **properties),
-						"audio/x-raw, format=F64%s, rate=%d".format(BYTE_ORDER, rate))
-	return transform.tag_inject(pipeline, caps, "instrument=%s,channel-name=%s,units=strain".format(instrument, channel_name))
+						"audio/x-raw, format=F64%s, rate=%d" % (BYTE_ORDER, rate))
+	return transform.tag_inject(pipeline, caps, "instrument=%s,channel-name=%s,units=strain" % (instrument, channel_name))
 
 
 def files(pipeline: pipetools.Pipeline, paths: Iterable[Union[str, pathlib.Path]], instrument: str, channel_name: str,
@@ -381,11 +381,11 @@ def files(pipeline: pipetools.Pipeline, paths: Iterable[Union[str, pathlib.Path]
 	cache_path = laltools.create_cache(entries=paths, cache_path=cache_path)
 	src = cache(pipeline, location=cache_path.as_posix())
 
-	demux = mux.framecpp_channel_demux(pipeline, src, do_file_checksum=False, channel_list=["%s:%s".format(instrument, channel_name)])
+	demux = mux.framecpp_channel_demux(pipeline, src, do_file_checksum=False, channel_list=["%s:%s" % (instrument, channel_name)])
 	mux.FrameCPPChannelDemuxSetUnitsHandler(demux, dict.fromkeys(demux.get_property("channel-list"), "strain"))
 
 	# allow frame reading and decoding to occur in a different thread
 	src = transform.queue(pipeline, None, max_size_buffers=0, max_size_bytes=0, max_size_time=8 * pipetools.Gst.SECOND)
-	SrcDeferredLink(demux, "%s:%s".format(instrument, channel_name), src.get_static_pad("sink"))
+	SrcDeferredLink(demux, "%s:%s" % (instrument, channel_name), src.get_static_pad("sink"))
 
 	return src