Remove unnecessary r-strings

Author: isullivan

python/lsst/pipe/tasks/skyCorrection.py

@@ -386,7 +386,7 @@ def run(self, calExps, calBkgs, skyFrames, camera, backgroundToPhotometricRatioH
         bgModel1Index = len(skyCorrs[0]._backgrounds)  # used to remove bgModel1 if undoBgModel1 is True
         for detector, skyCorr in zip(detectors, skyCorrs):
             with warnings.catch_warnings():
-                warnings.filterwarnings("ignore", r"invalid value encountered")
+                warnings.filterwarnings("ignore", "invalid value encountered")
                 calBkgElement = bgModel1.toCcdBackground(detector, detector.getBBox())
             skyCorr.append(calBkgElement[0])
 
@@ -431,7 +431,7 @@ def run(self, calExps, calBkgs, skyFrames, camera, backgroundToPhotometricRatioH
             # Update skyCorrs with new bgModel2 background elements
             for detector, skyCorr in zip(detectors, skyCorrs):
                 with warnings.catch_warnings():
-                    warnings.filterwarnings("ignore", r"invalid value encountered")
+                    warnings.filterwarnings("ignore", "invalid value encountered")
                     calBkgElement = bgModel2.toCcdBackground(detector, detector.getBBox())
                 skyCorr.append(calBkgElement[0])