.travis.yml: Drop superfluous use of --python=python3 parameter

As we require Python3 since commit ddf9069963, we don't need to
explicit it with the --python=/usr/bin/python3 configure option.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200125184217.30034-1-f4bug@amsat.org>
Message-Id: <20200203090932.19147-8-alex.bennee@linaro.org>

.travis.yml

@@ -270,7 +270,7 @@ matrix:
 
     # Acceptance (Functional) tests
     - env:
-        - CONFIG="--python=/usr/bin/python3 --target-list=x86_64-softmmu,mips-softmmu,mips64el-softmmu,aarch64-softmmu,arm-softmmu,s390x-softmmu,alpha-softmmu,ppc-softmmu,ppc64-softmmu,m68k-softmmu,sparc-softmmu"
+        - CONFIG="--target-list=x86_64-softmmu,mips-softmmu,mips64el-softmmu,aarch64-softmmu,arm-softmmu,s390x-softmmu,alpha-softmmu,ppc-softmmu,ppc64-softmmu,m68k-softmmu,sparc-softmmu"
         - TEST_CMD="make check-acceptance"
       after_script:
         - python3 -c 'import json; r = json.load(open("tests/results/latest/results.json")); [print(t["logfile"]) for t in r["tests"] if t["status"] not in ("PASS", "SKIP")]' | xargs cat