[Pillow] Removed python symlink (#12326)

Pillow's oss-fuzz is currently failing, because Pillow main has [dropped
support for Python
3.8](python-pillow/Pillow#8183).

#12027 attempts to resolve this by upgrading the base builder to Python
3.10, but the [latest status
update](#12027 (comment))
over there says that Pillow [fails in that branch
with](https://oss-fuzz-gcb-logs.storage.googleapis.com/log-e19625fb-a984-47b1-be32-f92b4c76fc7f.txt)
> Step 17: Step 6/11 : RUN ln -s /usr/local/bin/python3
/usr/local/bin/python && ln -s /bin/true /usr/local/bin/yum_install &&
ln -s /bin/true /usr/local/bin/yum && cd $SRC/Pillow && git submodule
update --init wheels/multibuild && bash $SRC/build_depends.sh
Step 17:  ---> Running in 932abd1dc89a
Step 17: �[91mln: failed to create symbolic link
'/usr/local/bin/python': File exists

So this pull request removes the python symlink in order to try and
help.

cc @hugovk

---------

Co-authored-by: Andrew Murray <[email protected]>

projects/pillow/Dockerfile

@@ -29,8 +29,7 @@ RUN $SRC/Pillow/Tests/oss-fuzz/build_dictionaries.sh
 
 COPY build_depends.sh $SRC
 
-RUN ln -s /usr/local/bin/python3 /usr/local/bin/python \
-    && ln -s /bin/true /usr/local/bin/yum_install \
+RUN ln -s /bin/true /usr/local/bin/yum_install \
     && ln -s /bin/true /usr/local/bin/yum \
     && cd $SRC/Pillow \
     && git submodule update --init wheels/multibuild \
@@ -44,7 +43,8 @@ RUN python3 -m pip install --upgrade pip
 COPY build.sh $SRC/
 
 # pillow optional runtime dependencies
-RUN apt-get install -y \
+RUN apt-get update && \
+    apt-get install -y \
      python3-tk \
      tcl8.6-dev \
      tk8.6-dev